3-amino-4-phenylbutanoic acid derivatives as dipeptidyl peptidase inhibitors for the treatment or prevention of diabetes

ABSTRACT

The present invention is directed to 3-amino-4-phenylbutanoic acid derivatives which are inhibitors of the dipeptidyl peptidase-IV enzyme (“DP-IV inhibitors”) and which are useful in the treatment or prevention of diseases in which the dipeptidyl peptidase-IV enzyme is involved, such as diabetes and particularly type 2 diabetes. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the prevention or treatment of such diseases in which the dipeptidyl peptidase-IV enzyme is involved.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/US04/002309, filed 27 Jan. 2004, which claims the benefit under 35U.S.C. 119(e) of U.S. Provisional Application No. 60/444,145 filed 31Jan. 2003.

BACKGROUND OF THE INVENTION

Diabetes refers to a disease process derived from multiple causativefactors and characterized by elevated levels of plasma glucose orhyperglycemia in the fasting state or after administration of glucoseduring an oral glucose tolerance test. Persistent or uncontrolledhyperglycemia is associated with increased and premature morbidity andmortality. Often abnormal glucose homeostasis is associated bothdirectly and indirectly with alterations of the lipid, lipoprotein andapolipoprotein metabolism and other metabolic and hemodynamic disease.Therefore patients with Type 2 diabetes mellitus are at especiallyincreased risk of macrovascular and microvascular complications,including coronary heart disease, stroke, peripheral vascular disease,hypertension, nephropathy, neuropathy, and retinopathy. Therefore,therapeutical control of glucose homeostasis, lipid metabolism andhypertension are critically important in the clinical management andtreatment of diabetes mellitus.

There are two generally recognized forms of diabetes. In type 1diabetes, or insulin-dependent diabetes mellitus (IDDM), patientsproduce little or no insulin, the hormone which regulates glucoseutilization. In type 2 diabetes, or noninsulin dependent diabetesmellitus (NIDDM), patients often have plasma insulin levels that are thesame or even elevated compared to nondiabetic subjects; however, thesepatients have developed a resistance to the insulin stimulating effecton glucose and lipid metabolism in the main insulin-sensitive tissues,which are muscle, liver and adipose tissues, and the plasma insulinlevels, while elevated, are insufficient to overcome the pronouncedinsulin resistance.

Insulin resistance is not primarily due to a diminished number ofinsulin receptors but to a post-insulin receptor binding defect that isnot yet understood. This resistance to insulin responsiveness results ininsufficient insulin activation of glucose uptake, oxidation and storagein muscle and inadequate insulin repression of lipolysis in adiposetissue and of glucose production and secretion in the liver.

The available treatments for type 2 diabetes, which have not changedsubstantially in many years, have recognized limitations. While physicalexercise and reductions in dietary intake of calories will dramaticallyimprove the diabetic condition, compliance with this treatment is verypoor because of well-entrenched sedentary lifestyles and excess foodconsumption, especially of foods containing high amounts of saturatedfat. Increasing the plasma level of insulin by administration ofsulfonylureas (e.g. tolbutamide and glipizide) or meglitinide, whichstimulate the pancreatic β-cells to secrete more insulin, and/or byinjection of insulin when sulfonylureas or meglitinide becomeineffective, can result in insulin concentrations high enough tostimulate the very insulin-resistant tissues. However, dangerously lowlevels of plasma glucose can result from administration of insulin orinsulin secretagogues (sulfonylureas or meglitinide), and an increasedlevel of insulin resistance due to the even higher plasma insulin levelscan occur. The biguanides increase insulin sensitivity resulting in somecorrection of hyperglycemia. However, the two biguanides, phenformin andmetformin, can induce lactic acidosis and nausea/diarrhea. Metformin hasfewer side effects than phenformin and is often prescribed for thetreatment of Type 2 diabetes.

The glitazones (i.e. 5-benzylthiazolidine-2,4-diones) are a morerecently described class of compounds with potential for amelioratingmany symptoms of type 2 diabetes. These agents substantially increaseinsulin sensitivity in muscle, liver and adipose tissue in severalanimal models of type 2 diabetes resulting in partial or completecorrection of the elevated plasma levels of glucose without occurrenceof hypoglycemia. The glitazones that are currently marketed are agonistsof the peroxisome proliferator activated receptor (PPAR), primarily thePPAR-gamma subtype. PPAR-gamma agonism is generally believed to beresponsible for the improved insulin sensititization that is observedwith the glitazones. Newer PPAR agonists that are being tested fortreatment of Type II diabetes are agonists of the alpha, gamma or deltasubtype, or a combination of these, and in many cases are chemicallydifferent from the glitazones (i.e., they are not thiazolidinediones).Serious side effects (e.g. liver toxicity) have occurred with some ofthe glitazones, such as troglitazone.

Additional methods of treating the disease are still underinvestigation. New biochemical approaches that have been recentlyintroduced or are still under development include treatment withalpha-glucosidase inhibitors (e.g. acarbose) and protein tyrosinephosphatase-1B (PTP-1B) inhibitors.

Compounds that are inhibitors of the dipeptidyl peptidase-IV (“DP-IV” or“DPP-IV”) enzyme are also under investigation as drugs that may beuseful in the treatment of diabetes, and particularly type 2 diabetes.See for example WO 97/40832, WO 98/19998, U.S. Pat. No. 5,939,560,Bioorg. Med. Chem. Lett., 6: 1163-1166 (1996); and Bioorg. Med. Chem.Lett. 6: 2745-2748 (1996). The usefulness of DP-IV inhibitors in thetreatment of type 2 diabetes is based on the fact that DP-IV in vivoreadily inactivates glucagon like peptide-1 (GLP-1) and gastricinhibitory peptide (GIP). GLP-1 and GIP are incretins and are producedwhen food is consumed. The incretins stimulate production of insulin.Inhibition of DP-IV leads to decreased inactivation of the incretins,and this in turn results in increased effectiveness of the incretins instimulating production of insulin by the pancreas. DP-IV inhibitiontherefore results in an increased level of serum insulin.Advantageously, since the incretins are produced by the body only whenfood is consumed, DP-IV inhibition is not expected to increase the levelof insulin at inappropriate times, such as between meals, which can leadto excessively low blood sugar (hypoglycemia). Inhibition of DP-IV istherefore expected to increase insulin without increasing the risk ofhypoglycemia, which is a dangerous side effect associated with the useof insulin secretagogues.

DP-IV inhibitors also have other therapeutic utilities, as discussedherein. DP-IV inhibitors have not been studied extensively to date,especially for utilities other than diabetes. New compounds are neededso that improved DP-IV inhibitors can be found for the treatment ofdiabetes and potentially other diseases and conditions. The therapeuticpotential of DP-IV inhibitors for the treatment of type 2 diabetes isdiscussed by D. J. Drucker in Exp. Opin. Invest. Drugs, 12: 87-100(2003) and by K. Augustyns, et al., in Exp. Opin. Ther. Patents, 13:499-510 (2003).

SUMMARY OF THE INVENTION

The present invention is directed to 3-amino-4-phenylbutanoic acidderivatives which are inhibitors of the dipeptidyl peptidase-IV enzyme(“DP-IV inhibitors”) and which are useful in the treatment or preventionof diseases in which the dipeptidyl peptidase-IV enzyme is involved,such as diabetes and particularly type 2 diabetes. The invention is alsodirected to pharmaceutical compositions comprising these compounds andthe use of these compounds and compositions in the prevention ortreatment of such diseases in which the dipeptidyl peptidase-IV enzymeis involved.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to 3-amino-4-phenylbutanoic acidderivatives useful as inhibitors of dipeptidyl peptidase-IV. Compoundsof the present invention are described by structural formula I:

or a pharmaceutically acceptable salt thereof; whereineach n is independently 0, 1, or 2;

-   -   W, X, Y, and Z are each independently N or CR¹;    -   with the provisos that at least one of W, X, Y and Z is CR¹, and        when W and Y are N, then one of X and Z is N;    -   Ar is phenyl substituted with one to five R² substituents;    -   each R¹ is independently selected from the group consisting of        -   hydrogen,        -   halogen,        -   hydroxy,        -   cyano,        -   C₁₋₁₀ alky, wherein alkyl is unsubstituted or substituted            with one to five substituents independently selected from            halogen or hydroxy,        -   C₁₋₁₀ alkoxy, wherein alkoxy is unsubstituted or substituted            with one to five substituents independently selected from            halogen or hydroxy,        -   C₁₋₁₀ alkylthio, wherein alkylthio is unsubstituted or            substituted with one to five substituents independently            selected from halogen or hydroxy,        -   C₂₋₁₀ alkenyl, wherein alkenyl is unsubstituted or            substituted with one to five substituents independently            selected from halogen, hydroxy, COOH, and COOC₁₋₆ alkyl,        -   (CH₂)_(n)COOH,        -   (CH₂)_(n)COOC₁₋₆ alkyl,        -   (CH₂)_(n)CONR³R⁴, wherein R³ and R⁴ are independently            selected from the group consisting of hydrogen, tetrazolyl,            thiazolyl, (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆ cycloalkyl, and            C₁₋₆ alkyl, wherein alkyl is unsubstituted or substituted            with one to five halogens and wherein phenyl and cycloalkyl            are unsubstituted or substituted with one to five            substituents independently selected from halogen, hydroxy,            C₁₋₆ alkyl, C₁₋₆ alkoxy, (CH₂)_(n)COOH, and (CH₂)_(n)COOC₁₋₆            alkyl, wherein alkyl and alkoxy are unsubstituted or            substituted with one to five halogens;            -   or R³ and R⁴ together with the nitrogen atom to which                they are attached form a heterocyclic ring selected from                azetidine, pyrrolidine, piperidine, piperazine, and                morpholine wherein said heterocyclic ring is                unsubstituted or substituted with one to five                substituents independently selected from halogen,                hydroxy, (CH₂)_(n)COOH, (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆                alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are                unsubstituted or substituted with phenyl or one to five                halogens;        -   (CH₂)_(n)—NR³R⁴,        -   (CH₂)_(n)—OCONR³R⁴,        -   (CH₂)_(n)—SO₂NR³R⁴,        -   (CH₂)_(n)—SO₂R⁵,        -   (CH₂)_(n)—NR⁶SO₂R⁵,        -   (CH₂)_(n)—NR⁶CONR³R⁴,        -   (CH₂)_(n)—NR⁶COR⁶,        -   (CH₂)_(n)—NR⁶CO₂R⁵,        -   (CH₂)_(n)—COR⁶,        -   (CH₂)_(n)—C₃₋₆ cycloalkyl, wherein cycloalkyl is            unsubstituted or substituted with one to three substituents            independently selected from halogen, hydroxy, C₁₋₆ alkyl,            and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted            or substituted with one to five halogens,        -   (CH₂)_(n)-aryl, wherein aryl is unsubstituted or substituted            with one to five substituents independently selected from            halogen, cyano, hydroxy, NR⁶SO₂R⁵, SO₂R⁵, CO₂H, COOC₁₋₆            alkyl, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy            are unsubstituted or substituted with one to five halogens,        -   (CH₂)_(n)-heteroaryl, wherein heteroaryl is unsubstituted or            substituted with one to three substituents independently            selected from hydroxy, halogen, C₁₋₆ alkyl, and C₁₋₆ alkoxy,            wherein alkyl and alkoxy are unsubstituted or substituted            with one to five halogens, and        -   (CH₂)_(n)-heterocyclyl, wherein heterocyclyl is            unsubstituted or substituted with one to three substituents            independently selected from oxo, hydroxy, halogen, C₁₋₆            alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are            unsubstituted or substituted with one to five halogens,        -   wherein any methylene (CH₂) carbon atom in R¹ is            unsubstituted or substituted with one to two groups            independently selected from halogen, hydroxy, and C₁₋₄ alkyl            unsubstituted or substituted with one to five halogens;    -   each R² is independently selected from the group consisting of        -   hydrogen,        -   halogen,        -   cyano,        -   hydroxy,        -   C₁₋₆ alkyl, unsubstituted or substituted with one to five            halogens, and        -   C₁₋₆ alkoxy, unsubstituted or substituted with one to five            halogens;    -   each R⁵ is independently selected from the group consisting of        tetrazolyl, thiazolyl, (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆        cycloalkyl, and C₁₋₆ alkyl, wherein alkyl is unsubstituted or        substituted with one to five halogens and wherein phenyl and        cycloalkyl are unsubstituted or substituted with one to five        substituents independently selected from halogen, hydroxy, C₁₋₆        alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are        unsubstituted or substituted with one to five halogens, and        wherein any methylene (CH₂) carbon atom in R⁵ is unsubstituted        or substituted with one to two groups independently selected        from halogen, hydroxy, C₁₋₄ alkyl, and C₁₋₄ alkoxy, wherein        alkyl and alkoxy are unsubstituted or substituted with one to        five halogens;    -   each R⁶ is hydrogen or R⁵;    -   R⁷, R⁸, and R⁹ are each independently selected from the group        consisting of        -   hydrogen,        -   cyano,        -   (CH₂)_(n)COOH,        -   (CH₂)_(n)COOC₁₋₆ alkyl,        -   C₁₋₁₀ alkyl, unsubstituted or substituted with one to five            substituents independently selected from halogen, hydroxy,            C₁₋₆ alkoxy, and phenyl-C₁₋₃ alkoxy, wherein alkoxy is            unsubstituted or substituted with one to five halogens,        -   (CH₂)_(n)-aryl, wherein aryl is unsubstituted or substituted            with one to five substituents independently selected from            halogen, hydroxy, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl            and alkoxy are unsubstituted or substituted with one to five            halogens,        -   (CH₂)_(n)-heteroaryl, wherein heteroaryl is unsubstituted or            substituted with one to three substituents independently            selected from hydroxy, halogen, C₁₋₆ alkyl, and C₁₋₆ alkoxy,            wherein alkyl and alkoxy are unsubstituted or substituted            with one to five halogens,        -   (CH₂)_(n)-heterocyclyl, wherein heterocyclyl is            unsubstituted or substituted with one to three substituents            independently selected from oxo, hydroxy, halogen, C₁₋₆            alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are            unsubstituted or substituted with one to five halogens,        -   (CH₂)_(n)—C₃₋₆ cycloalkyl, wherein cycloalkyl is            unsubstituted or substituted with one to three substituents            independently selected from halogen, hydroxy, C₁₋₆ alkyl,            and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted            or substituted with one to five halogens, and        -   (CH₂)_(n)CONR³R⁴, wherein R³ and R⁴ are independently            selected from the group consisting of hydrogen, tetrazolyl,            thiazolyl, (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆ cycloalkyl, and            C₁₋₆ alkyl, wherein alkyl is unsubstituted or substituted            with one to five halogens and wherein phenyl and cycloalkyl            are unsubstituted or substituted with one to five            substituents independently selected from halogen, hydroxy,            C₁₋₆ alkyl, C₁₋₆ alkoxy, (CH₂)_(n)COOH, and (CH₂)_(n)COOC₁₋₆            alkyl, wherein alkyl and alkoxy are unsubstituted or            substituted with one to five halogens;            -   or R³ and R⁴ together with the nitrogen atom to which                they are attached form a heterocyclic ring selected from                azetidine, pyrrolidine, piperidine, piperazine, and                morpholine wherein said heterocyclic ring is                unsubstituted or substituted with one to five                substituents independently selected from halogen,                hydroxy, (CH₂)_(n)COOH, (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆                alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are                unsubstituted or substituted with phenyl or one to five                halogens; and        -   wherein any methylene (CH₂) carbon atom in R⁷, R⁸ or R⁹ is            unsubstituted or substituted with one to two groups            independently selected from halogen, hydroxy, and C₁₋₄ alkyl            unsubstituted or substituted with one to five halogens.

In one embodiment of the compounds of the present invention, the carbonatom marked with an * has the R stereochemical configuration as depictedin formula Ia

wherein Ar, W, X, Y, Z, R⁷, R⁸, and R⁹ are as defined herein.

In a second embodiment of the compounds of the present invention, W, X,Y, and Z are CR¹ as depicted in formula Ib:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this second embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Ic:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this second embodiment of the compounds of thepresent invention, R⁷ and R⁹ are hydrogen as depicted in formula Id:

wherein Ar, R¹, and R⁸ are as defined herein.

In a subclass of this class, R⁸ is CONR³R⁴ or hydrogen.

In a third embodiment of the compounds of the present invention, W, X,and Y are CR¹ and Z is N as depicted in formula Ie:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this third embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula If:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this third embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Ig:

wherein Ar, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In a fourth embodiment of the compounds of the present invention, W, X,and Z are CR¹, and Y is N as depicted in formula Ih:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this fourth embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Ii:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this fourth embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Ij:

wherein Ar, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In a fifth embodiment of the compounds of the present invention, W is N,and X, Y, and Z are CR¹ as depicted in formula Ik:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this fifth embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Il:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this fifth embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Im:

wherein Ar,¹, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In a sixth embodiment of the compounds of the present invention, W isCR¹, X is N, Y is CR¹, and Z is N as depicted in formula In:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this sixth embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Io:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this sixth embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Ip:

wherein Ar, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In a seventh embodiment of the compounds of the present invention, W isN, X and Y are CR¹, and Z is N as depicted in formula Iq:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this seventh embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Ir:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this seventh embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Is:

wherein Ar, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In an eighth embodiment of the compounds of the present invention, W andX are N, and Y and Z are CR¹ as depicted in formula It:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this eighth embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Iu:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this eighth embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Iv:

wherein Ar, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In a ninth embodiment of the compounds of the present invention, W, X,and Z are N, and Y is CR¹ as depicted in formula Iw:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this ninth embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Ix:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this ninth embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Iy:

wherein Ar, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In a tenth embodiment of the compounds of the present invention, W, Y,and Z are N, and X is CR¹ as depicted in formula Iz:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In a class of this tenth embodiment, the carbon atom marked with an *has the R stereochemical configuration as depicted in formula Iaa:

wherein Ar, R¹, R⁷, R⁸, and R⁹ are as defined herein.

In another class of this tenth embodiment of the compounds of thepresent invention, R⁸ and R⁹ are hydrogen as depicted in formula Iab:

wherein Ar, R¹, and R⁷ are as defined herein.

In a subclass of this class, R⁷ is hydrogen.

In an eleventh embodiment of the compounds of the present invention, R²is selected from the group consisting of hydrogen, fluoro, chloro,bromo, trifluoromethyl, and methyl. In a class of this embodiment, R² isselected from the group consisting of hydrogen, fluoro, and chloro. In asubclass of this class, R² is hydrogen or fluoro.

In a twelfth embodiment of the compounds of the present invention, R¹ isselected from the group consisting of:

-   -   hydrogen,    -   halogen,    -   hydroxy,    -   cyano,    -   C₁₋₁₀ alkyl, wherein alkyl is unsubstituted or substituted with        one to five substituents independently selected from halogen or        hydroxy,    -   C₁₋₁₀ alkoxy, wherein alkoxy is unsubstituted or substituted        with one to five substituents independently selected from        halogen or hydroxy,    -   (CH₂)_(n)COOH,    -   (CH₂)_(n)COOC₁₋₆ alkyl,    -   (CH₂)_(n)CONR³R⁴, wherein R³ and R⁴ are independently selected        from the group consisting of hydrogen, tetrazolyl, thiazolyl,        (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆ cycloalkyl, and C₁₋₆ alkyl,        wherein alkyl is unsubstituted or substituted with one to five        halogens and wherein phenyl and cycloalkyl are unsubstituted or        substituted with one to five substituents independently selected        from halogen, hydroxy, C₁₋₆ alky, C₁₋₆ alkoxy, (CH₂)_(n)COOH,        and (CH₂)_(n)COOC₁₋₆ alkyl, wherein alkyl and alkoxy are        unsubstituted or substituted with one to five halogens;    -    or R³ and R⁴ together with the nitrogen atom to which they are        attached form a heterocyclic ring selected from azetidine,        pyrrolidine, piperidine, piperazine, and morpholine wherein said        heterocyclic ring is unsubstituted or substituted with one to        five substituents independently selected from halogen, hydroxy,        (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein        alkyl and alkoxy are unsubstituted or substituted with phenyl or        one to five halogens;    -   (CH₂)_(n)—SO₂NR³R⁴,    -   (CH₂)_(n)—NR⁶SO₂R⁵,    -   (CH₂)_(n)—NR⁶COR⁶,    -   (CH₂)_(n)—C₃₋₆ cycloalkyl, wherein cycloalkyl is unsubstituted        or substituted with one to three substituents independently        selected from halogen, hydroxy, C₁₋₆ alkyl, and C₁₋₆ alkoxy,        wherein alkyl and alkoxy are unsubstituted or substituted with        one to five halogens,    -   (CH₂)_(n)-aryl, wherein aryl is unsubstituted or substituted        with one to five substituents independently selected from        halogen, cyano, hydroxy, NR⁶SO₂R⁵, SO₂R⁵, CO₂H, COOC₁₋₆ alkyl,        C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are        unsubstituted or substituted with one to five halogens,    -   (CH₂)_(n)-heteroaryl, wherein heteroaryl is unsubstituted or        substituted with one to three substituents independently        selected from hydroxy, halogen, C₁₋₆ alkyd, and C₁₋₆ alkoxy,        wherein alkyl and alkoxy are unsubstituted or substituted with        one to five halogens, and    -   wherein any methylene (CH₂) carbon atom in R¹ is unsubstituted        or substituted with one to two groups independently selected        from halogen, hydroxy, and C₁₋₄ alkyl unsubstituted or        substituted with one to five halogens.

In a class of this embodiment of the compounds of the present invention,R¹ is selected from the group consisting of

-   -   hydrogen,    -   methyl,    -   trifluoromethyl,    -   phenyl,    -   4-fluorophenyl,    -   cyclopropyl,    -   chloro,    -   methoxy,    -   hydroxy,    -   cyano,    -   methoxycarbonyl,    -   ethoxycarbonyl,    -   tert-butylaminocarbonyl,    -   carboxy,    -   acetamido,    -   methanesulfonylamino,    -   benzenesulfonylamino,    -   aminosulfonyl, and    -   5-(trifluoromethyl)oxadiazol-3-yl.

In a thirteenth embodiment of the compounds of the present invention,R⁷, R⁸, and R⁹ are independently selected from the group consisting of:

-   -   hydrogen,    -   C₁₋₁₀ alkyl, unsubstituted or substituted with one to five        substituents independently selected from halogen, hydroxy, C₁₋₆        alkoxy, and phenyl-C₁₋₃ alkoxy, wherein alkoxy is unsubstituted        or substituted with one to five halogens, and    -   (CH₂)_(n)CONR³R⁴, wherein R³ and R⁴ are independently selected        from the group consisting of hydrogen, tetrazolyl, thiazolyl,        (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆ cycloalkyl, and C₁₋₆ alkyl,        wherein alkyl is unsubstituted or substituted with one to five        halogens and wherein phenyl and cycloalkyl are unsubstituted or        substituted with one to five substituents independently selected        from halogen, hydroxy, C₁₋₆ alkyl, C₁₋₆ alkoxy, (CH₂)_(n)COOH,        and (CH₂)_(n)COOC₁₋₆ alkyl, wherein alkyl and alkoxy are        unsubstituted or substituted with one to five halogens;    -    or R³ and R⁴ together with the nitrogen atom to which they are        attached form a heterocyclic ring selected from azetidine,        pyrrolidine, piperidine, piperazine, and morpholine wherein said        heterocyclic ring is unsubstituted or substituted with one to        five substituents independently selected from halogen, hydroxy,        (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein        alkyl and alkoxy are unsubstituted or substituted with phenyl or        one to five halogens; and

wherein any methylene (CH₂) carbon atom in R⁷, R⁸ or R⁹ is unsubstitutedor substituted with one to two groups independently selected fromhalogen, hydroxy, and C₁₋₄ alkyl unsubstituted or substituted with oneto five halogens.

In a class of this embodiment of the compounds of the present invention,R⁷, R⁸, and R⁹ are each independently selected from the group consistingof

-   -   hydrogen,    -   methyl,    -   ethyl,    -   [[4-(carboxymethyl)phenyl]methyl]aminocarbonyl,    -   pyrrolidin-1-ylcarbonyl,    -   piperidin-1-ylcarbonyl,    -   4-[(methoxycarbonyl)methyl]benzylaminocarbonyl, and    -   4-[(benzyloxy)carbonyl]piperazin-1-ylcarbonyl.

In a subclass of this class, R⁷ and R⁹ are hydrogen.

In a further subclass of this class, R⁸ and R⁹ are hydrogen. In asubclass of this subclass, R⁷ is hydrogen.

Illustrative, but nonlimiting, examples of compounds of the presentinvention that are useful as dipeptidyl peptidase-IV inhibitors are thefollowing:

or a pharmaceutically acceptable salt thereof.

As used herein the following definitions are applicable.

“Alkyl” well as other groups having the prefix “alk”, such as alkoxy andalkanoyl, means carbon chains which may be linear or branched, andcombinations thereof, unless the carbon chain is defined otherwise.Examples of alkyl groups include methyl, ethyl, propyl, isopropyl,butyl, sec- and tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and thelike. Where the specified number of carbon atoms permits, e.g., fromC₃₋₁₀, the term alkyl also includes cycloalkyl groups, and combinationsof linear or branched alkyl chains combined with cycloalkyl structures.When no number of carbon atoms is specified, C₁₋₆ is intended.

“Cycloalkyl” is a subset of alkyl and means a saturated carbocyclic ringhaving a specified number of carbon atoms. Examples of cycloalkylinclude cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, and the like. A cycloalkyl group generally is monocyclicunless stated otherwise. Cycloalkyl groups are saturated unlessotherwise defined.

The term “alkoxy” refers to straight or branched chain alkoxides of thenumber of carbon atoms specified (e.g., C₁₋₁₀ alkoxy), or any numberwithin this range [i.e., methoxy (MeO—), ethoxy, isopropoxy, etc.].

The term “alkylthio” refers to straight or branched chain alkylsulfidesof the number of carbon atoms specified (e.g., C₁₋₁₀ alkylthio), or anynumber within this range [i.e., methylthio (MeS—), ethylthio,isopropylthio, etc.].

The term “alkylamino” refers to straight or branched alkylamines of thenumber of carbon atoms specified (e.g., C₁₋₆ alkylamino), or any numberwithin this range [i.e., methylamino, ethylamino, isopropylamino,t-butylamino, etc.].

The term “alkylsulfonyl” refers to straight or branched chainalkylsulfones of the number of carbon atoms specified (e.g., C₁₋₆alkylsulfonyl), or any number within this range [i.e., methylsulfonyl(MeSO₂—), ethylsulfonyl, isopropylsulfonyl, etc.].

The term “alkyloxycarbonyl” refers to straight or branched chain estersof a carboxylic acid derivative of the present invention of the numberof carbon atoms specified (e.g., C₁₋₆ alkyloxycarbonyl), or any numberwithin this range [i.e., methyloxycarbonyl (MeOCO—), ethyloxycarbonyl,or butyloxycarbonyl].

“Aryl” means a mono- or polycyclic aromatic ring system containingcarbon ring atoms. The preferred aryls are monocyclic or bicyclic 6-10membered aromatic ring systems. Phenyl and naphthyl are preferred aryls.The most preferred aryl is phenyl.

“Heterocycle” and “heterocyclyl” refer to saturated or unsaturatednon-aromatic rings or ring systems containing at least one heteroatomselected from O, S and N, further including the oxidized forms ofsulfur, namely SO and SO₂. Examples of heterocycles includetetrahydrofuran (THF), dihydrofuran, 1,4-dioxane, morpholine,1,4-dithiane, piperazine, piperidine, 1,3-dioxolane, imidazolidine,imidazoline, pyrroline, pyrrolidine, tetrahydropyran, dihydropyran,oxathiolane, dithiolane, 1,3-dioxane, 1,3-dithiane, oxathiane,thiomorpholine, and the like.

“Heteroaryl” means an aromatic or partially aromatic heterocycle thatcontains at least one ring heteroatom selected from O, S and N.Heteroaryls also include heteroaryls fused to other kinds of rings, suchas aryls, cycloalkyls and heterocycles that are not aromatic. Examplesof heteroaryl groups include pyrrolyl, isoxazolyl, isothiazolyl,pyrazolyl, pyridinyl, 2-oxo-(1H)-pyridinyl (2-hydroxy-pyridinyl),oxazolyl, 1,2,4-oxadiazolyl, 1,3,4-oxadiazolyl, thiadiazolyl, thiazolyl,imidazolyl, triazolyl, tetrazolyl, furyl, triazinyl, thienyl,pyrimidinyl, pyrazinyl, benzisoxazolyl, benzoxazolyl, benzothiazolyl,benzothiadiazolyl, dihydrobenzofuranyl, indolinyl, pyridazinyl,indazolyl, isoindolyl, dihydrobenzothienyl, indolizinyl, cinnolinyl,phthalazinyl, quinazolinyl, naphthyridinyl, carbazolyl, benzodioxolyl,quinoxalinyl, purinyl, furazanyl, isobenzylfuranyl, benzimidazolyl,benzofuranyl, benzothienyl, quinolyl, indolyl, isoquinolyl,dibenzofuranyl, imidazo[1,2-a]pyridinyl,[1,2,4-triazolo][4,3-a]pyridinyl, pyrazolo[1,5-a]pyridinyl,[1,2,4-triazolo][1,5-a]pyridinyl, 2-oxo-1,3-benzoxazolyl,4-oxo-3H-quinazolinyl, 3-oxo-[1,2,4]-triazolo[4,3-a]-2H-pyridinyl,5-oxo-[1,2,4]-4H-oxadiazolyl, 2-oxo-[1,3,4]-3H-oxadiazolyl,2-oxo-1,3-dihydro-2H-imidazolyl, 3-oxo-2,4-dihydro-3H-1,2,4-triazolyl,and the like. For heterocyclyl and heteroaryl groups, rings and ringsystems containing from 3-15 atoms are included, forming 1-3 rings.

“Halogen” refers to fluorine, chlorine, bromine and iodine. Chlorine andfluorine are generally preferred. Fluorine is most preferred when thehalogens are substituted on an alkyl or alkoxy group (e.g. CF₃O andCF₃CH₂O).

The compounds of the present invention may contain one or moreasymmetric centers and can thus occur as racemates and racemic mixtures,single enantiomers, diastereomeric mixtures and individualdiastereomers. The compounds of the present invention have oneasymmetric center at the carbon atom marked with an * in formula Ia.Additional asymmetric centers may be present depending upon the natureof the various substituents on the molecule. Each such asymmetric centerwill independently produce two optical isomers and it is intended thatall of the possible optical isomers and diastereomers in mixtures and aspure or partially purified compounds are included within the ambit ofthis invention. The present invention is meant to comprehend all suchisomeric forms of these compounds.

Some of the compounds described herein contain olefinic double bonds,and unless specified otherwise, are meant to include both E and Zgeometric isomers.

Some of the compounds described herein may exist as tautomers, whichhave different points of attachment of hydrogen accompanied by one ormore double bond shifts. For example, a ketone and its enol form areketo-enol tautomers. The individual tautomers as well as mixturesthereof are encompassed with compounds of the present invention.

Formula I shows the structure of the class of compounds withoutpreferred stereochemistry. Formula Ia shows the preferred sterochemistryat the carbon atom to which is attached the amino group of the betaamino acid from which these compounds are prepared.

The independent syntheses of these diastereomers or theirchromatographic separations may be achieved as known in the art byappropriate modification of the methodology disclosed herein. Theirabsolute stereochemistry may be determined by the x-ray crystallographyof crystalline products or crystalline intermediates which arederivatized, if necessary, with a reagent containing an asymmetriccenter of known absolute configuration.

If desired, racemic mixtures of the compounds may be separated so thatthe individual enantiomers are isolated. The separation can be carriedout by methods well known in the art, such as the coupling of a racemicmixture of compounds to an enantiomerically pure compound to form adiastereomeric mixture, followed by separation of the individualdiastereomers by standard methods, such as fractional crystallization orchromatography. The coupling reaction is often the formation of saltsusing an enantiomerically pure acid or base. The diasteromericderivatives may then be converted to the pure enantiomers by cleavage ofthe added chiral residue. The racemic mixture of the compounds can alsobe separated directly by chromatographic methods utilizing chiralstationary phases, which methods are well known in the art.

Alternatively, any enantiomer of a compound may be obtained bystereoselective synthesis using optically pure starting materials orreagents of known configuration by methods well known in the art.

It will be understood that, as used herein, references to the compoundsof structural formula I are meant to also include the pharmaceuticallyacceptable salts, and also salts that are not pharmaceuticallyacceptable when they are used as precursors to the free compounds ortheir pharmaceutically acceptable salts or in other syntheticmanipulations.

The compounds of the present invention may be administered in the formof a pharmaceutically acceptable salt. The term “pharmaceuticallyacceptable salt” refers to salts prepared from pharmaceuticallyacceptable non-toxic bases or acids including inorganic or organic basesand inorganic or organic acids. Salts of basic compounds encompassedwithin the term “pharmaceutically acceptable salt” refer to non-toxicsalts of the compounds of this invention which are generally prepared byreacting the free base with a suitable organic or inorganic acid.Representative salts of basic compounds of the present inventioninclude, but are not limited to, the following: acetate,benzenesulfonate, benzoate, bicarbonate, bisulfate, bitartrate, borate,bromide, camsylate, carbonate, chloride, clavulanate, citrate,dihydrochloride, edetate, edisylate, estolate, esylate, fumarate,gluceptate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate,hydrabamine, hydrobromide, hydrochloride, hydroxynaphthoate, iodide,isothionate, lactate, lactobionate, laurate, malate, maleate, mandelate,mesylate, methylbromide, methylnitrate, methylsulfate, mucate,napsylate, nitrate, N-methylglucamine ammonium salt, oleate, oxalate,pamoate (embonate), palmitate, pantothenate, phosphate/diphosphate,polygalacturonate, salicylate, stearate, sulfate, subacetate, succinate,tannate, tartrate, teoclate, tosylate, triethiodide and valerate.Furthermore, where the compounds of the invention carry an acidicmoiety, suitable pharmaceutically acceptable salts thereof include, butare not limited to, salts derived from inorganic bases includingaluminum, ammonium, calcium, copper, ferric, ferrous, lithium,magnesium, manganic, mangamous, potassium, sodium, zinc, and the like.Particularly preferred are the ammonium, calcium, magnesium, potassium,and sodium salts. Salts derived from pharmaceutically acceptable organicnon-toxic bases include salts of primary, secondary, and tertiaryamines, cyclic amines, and basic ion-exchange resins, such as arginine,betaine, caffeine, choline, N,N-dibenzylethylenediamine, diethylamine,2-diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine,ethylenediamine, N-ethylmorpholine, N-ethylpiperidine, glucamine,glucosamine, histidine, hydrabamine, isopropylamine, lysine,methylglucamine, morpholine, piperazine, piperidine, polyamine resins,procaine, purines, theobromine, triethylamine, trimethylamine,tripropylamine, tromethamine, and the like.

Also, in the case of a carboxylic acid (—COOH) or alcohol group beingpresent in the compounds of the present invention, pharmaceuticallyacceptable esters of carboxylic acid derivatives, such as methyl, ethyl,or pivaloyloxymethyl, or acyl derivatives of alcohols, such as acetateor maleate, can be employed. Included are those esters and acyl groupsknown in the art for modifying the solubility or hydrolysischaracteristics for use as sustained-release or prodrug formulations.

Solvates, and in particular, the hydrates of the compounds of structuralformula I are included in the present invention as well.

Exemplifying the invention is the use of the compounds disclosed in theExamples and herein.

The subject compounds are useful in a method of inhibiting thedipeptidyl peptidase-IV enzyme in a patient such as a mammal in need ofsuch inhibition comprising the administration of an effective amount ofthe compound. The present invention is directed to the use of thecompounds disclosed herein as inhibitors of dipeptidyl peptidase-IVenzyme activity.

In addition to primates, such as humans, a variety of other mammals canbe treated according to the method of the present invention. Forinstance, mammals including, but not limited to, cows, sheep, goats,horses, dogs, cats, guinea pigs, rats or other bovine, ovine, equine,canine, feline, rodent or murine species can be treated. However, themethod can also be practiced in other species, such as avian species(e.g., chickens).

The present invention is further directed to a method for themanufacture of a medicament for inhibiting dipeptidyl peptidase-IVenzyme activity in humans and animals comprising combining a compound ofthe present invention with a pharmaceutically acceptable carrier ordiluent.

The subject treated in the present methods is generally a mammal,preferably a human being, male or female, in whom inhibition ofdipeptidyl peptidase-IV enzyme activity is desired. The term“therapeutically effective amount” means the amount of the subjectcompound that will elicit the biological or medical response of atissue, system, animal or human that is being sought by the researcher,veterinarian, medical doctor or other clinician.

The term “composition” as used herein is intended to encompass a productcomprising the specified ingredients in the specified amounts, as wellas any product which results, directly or indirectly, from combinationof the specified ingredients in the specified amounts. Such term inrelation to pharmaceutical composition, is intended to encompass aproduct comprising the active ingredient(s), and the inert ingredient(s)that make up the carrier, as well as any product which results, directlyor indirectly, from combination, complexation or aggregation of any twoor more of the ingredients, or from dissociation of one or more of theingredients, or from other types of reactions or interactions of one ormore of the ingredients. Accordingly, the pharmaceutical compositions ofthe present invention encompass any composition made by admixing acompound of the present invention and a pharmaceutically acceptablecarrier. By “pharmaceutically acceptable” it is meant the carrier,diluent or excipient must be compatible with the other ingredients ofthe formulation and not deleterious to the recipient thereof.

The terms “administration of” and or “administering a” compound shouldbe understood to mean providing a compound of the invention or a prodrugof a compound of the invention to the individual in need of treatment.

The utility of the compounds in accordance with the present invention asinhibitors of dipeptidyl peptidase-IV enzyme activity may bedemonstrated by methodology known in the art. Inhibition constants aredetermined as follows. A continuous fluorometric assay is employed withthe substrate Gly-Pro-AMC, which is cleaved by DP-IV to release thefluorescent AMC leaving group. The kinetic parameters that describe thisreaction are as follows: K_(m)=50 μM; k_(cat)=75 s⁻¹;k_(cat)/K_(m)=1.5×10⁶ M⁻¹s⁻¹. A typical reaction contains approximately50 pM enzyme, 50 μM Gly-Pro-AMC, and buffer (100 mM HEPES, pH 7.5, 0.1mg/ml BSA) in a total reaction volume of 100 μl. Liberation of AMC ismonitored continuously in a 96-well plate fluorometer using anexcitation wavelength of 360 nm and an emission wavelength of 460 nm.Under these conditions, approximately 0.8 μM AMC is produced in 30minutes at 25 degrees C. The enzyme used in these studies was soluble(transmembrane domain and cytoplasmic extension excluded) human proteinproduced in a baculovirus expression system (Bac-To-Bac, Gibco BRL). Thekinetic constants for hydrolysis of Gly-Pro-AMC and GLP-1 were found tobe in accord with literature values for the native enzyme. To measurethe dissociation constants for compounds, solutions of inhibitor in DMSOwere added to reactions containing enzyme and substrate (final DMSOconcentration is 1%). All experiments were conducted at room temperatureusing the standard reaction conditions described above. To determine thedissociation constants (K_(i)), reaction rates were fit by non-linearregression to the Michaelis-Menton equation for competitive inhibition.The errors in reproducing the dissociation constants are typically lessthan two-fold.

In particular, the compounds of the following examples had activity ininhibiting the dipeptidyl peptidase-IV enzyme in the aforementionedassays, generally with an IC₅₀ of less than about 1 μM. Such a result isindicative of the intrinsic activity of the compounds in use asinhibitors of the dipeptidyl peptidase-IV enzyme activity.

Dipeptidyl peptidase-IV enzyme (DP-IV) is a cell surface protein thathas been implicated in a wide range of biological functions. It has abroad tissue distribution (intestine, kidney, liver, pancreas, placenta,thymus, spleen, epithelial cells, vascular endothelium, lymphoid andmyeloid cells, serum), and distinct tissue and cell-type expressionlevels. DP-IV is identical to the T cell activation marker CD26, and itcan cleave a number of immunoregulatory, endocrine, and neurologicalpeptides in vitro. This has suggested a potential role for thispeptidase in a variety of disease processes in humans or other species.

Accordingly, the subject compounds are useful in a method for theprevention or treatment of the following diseases, disorders andconditions.

-   Type II Diabetes and Related Disorders: It is well established that    the incretins GLP-1 and GIP are rapidly inactivated in vivo by    DP-IV. Studies with DP-IV^((−/−))-deficient mice and preliminary    clinical trials indicate that DP-IV inhibition increases the steady    state concentrations of GLP-1 and GIP, resulting in improved glucose    tolerance. By analogy to GLP-1 and GIP, it is likely that other    glucagon family peptides involved in glucose regulation are also    inactivated by DP-IV (eg. PACAP). Inactivation of these peptides by    DP-IV may also play a role in glucose homeostasis. The DP-IV    inhibitors of the present invention therefore have utility in the    treatment of type II diabetes and in the treatment and prevention of    the numerous conditions that often accompany Type II diabetes,    including Syndrome X (also known as Metabolic Syndrome), reactive    hypoglycemia, and diabetic dyslipidemia. Obesity, discussed below,    is another condition that is often found with Type II diabetes that    may respond to treatment with the compounds of this invention.

The following diseases, disorders and conditions are related to Type 2diabetes, and therefore may be treated, controlled or in some casesprevented, by treatment with the compounds of this invention: (1)hyperglycemia, (2) low glucose tolerance, (3) insulin resistance, (4)obesity, (5) lipid disorders, (6) dyslipidemia, (7) hyperlipidemia, (8)hypertriglyceridemia, (9) hypercholesterolemia, (10) low HDL levels,(11) high LDL levels, (12) atherosclerosis and its sequelae, (13)vascular restenosis, (14) irritable bowel syndrome, (15) inflammatorybowel disease, including Crohn's disease and ulcerative colitis, (16)other inflammatory conditions, (17) pancreatitis, (18) abdominalobesity, (19) neurodegenerative disease, (20) retinopathy, (21)nephropathy, (22) neuropathy, (23) Syndrome X, (24) ovarianhyperandrogenism (polycystic ovarian syndrome), and other disorderswhere insulin resistance is a component. In Syndrome X, also known asMetabolic Syndrome, obesity is thought to promote insulin resistance,diabetes, dyslipidemia, hypertension, and increased cardiovascular risk.Therefore, DP-IV inhibitors may also be useful to treat hypertensionassociated with this condition.

-   Obesity: DP-IV inhibitors may be useful for the treatment of    obesity. This is based on the observed inhibitory effects on food    intake and gastric emptying of GLP-1 and GLP-2. Exogenous    administration of GLP-1 in humans significantly decreases food    intake and slows gastric emptying (Am. J. Physiol., 277: R910-R916    (1999)). ICV administration of GLP-1 in rats and mice also has    profound effects on food intake (Nature Medicine, 2: 1254-1258    (1996)). This inhibition of feeding is not observed in    GLP-1R^((−/−)) mice, indicating that these effects are mediated    through brain GLP-1 receptors. By analogy to GLP-1, it is likely    that GLP-2 is also regulated by DP-IV. ICV administration of GLP-2    also inhibits food intake, analogous to the effects observed with    GLP-1 (Nature Medicine, 6: 802-807 (2000)). In addition, studies    with DP-IV deficient mice suggest that these animals are resistant    to diet-induced obesity and associated pathology (e.g.    hyperinsulinonemia).-   Growth Hormone Deficiency: DP-IV inhibition may be useful for the    treatment of growth hormone deficiency, based on the hypothesis that    growth-hormone releasing factor (GRF), a peptide that stimulates    release of growth hormone from the anterior pituitary, is cleaved by    the DP-IV enzyme in vivo (WO 00/56297). The following data provide    evidence that GRF is an endogenous substrate: (1) GRF is efficiently    cleaved in vitro to generate the inactive product GRF[3-44] (BBA    1122: 147-153 (1992)); (2) GRF is rapidly degraded in plasma to    GRF[3-44]; this is prevented by the DP-IV inhibitor diprotin A;    and (3) GRF[344] is found in the plasma of a human GRF transgenic    pig (J. Clin. Invest., 83: 1533-1540 (1989)). Thus DP-IV inhibitors    may be useful for the same spectrum of indications which have been    considered for growth hormone secretagogues.-   Intestinal Injury: The potential for using DP-IV inhibitors for the    treatment of intestinal injury is suggested by the results of    studies indicating that glucagon-like peptide-2 (GLP-2), a likely    endogenous substrate for DP-IV, may exhibit trophic effects on the    intestinal epithelium (Regulatory Peptides. 90: 27-32 (2000)).    Administration of GLP-2 results in increased small bowel mass in    rodents and attenuates intestinal injury in rodent models of colitis    and enteritis.-   Immunosuppression: DP-IV inhibition may be useful for modulation of    the immune response, based upon studies implicating the DP-IV enzyme    in T cell activation and in chemokine processing, and efficacy of    DP-IV inhibitors in in vivo models of disease. DP-IV has been shown    to be identical to CD26, a cell surface marker for activated immune    cells. The expression of CD26 is regulated by the differentiation    and activation status of immune cells. It is generally accepted that    CD26 functions as a co-stimulatory molecule in in vitro models of T    cell activation. A number of chemokines contain proline in the    penultimate position, presumably to protect them from degradation by    non-specific aminopeptidases. Many of these have been shown to be    processed in vitro by DP-IV. In several cases (RANTES, LD78-beta,    MDC, eotaxin, SDF-1alpha), cleavage results in an altered activity    in chemotaxis and signaling assays. Receptor selectivity also    appears to be modified in some cases (RANTES). Multiple N-terminally    truncated forms of a number of chemokines have been identified in in    vitro cell culture systems, including the predicted products of    DP-IV hydrolysis.

DP-IV inhibitors have been shown to be efficacious immunosuppressants inanimal models of transplantation and arthritis. Prodipine(Pro-Pro-diphenyl-phosphonate), an irreversible inhibitor of DP-IV, wasshown to double cardiac allograft survival in rats from day 7 to day 14(Transplantation 63: 1495-1500 (1997)). DP-IV inhibitors have beentested in collagen and alkyldiamine-induced arthritis in rats and showeda statistically significant attenuation of hind paw swelling in thismodel [Int. J. Immunopharmacology, 19:15-24 (1997) andImmunopharmacology, 40: 21-26 (1998)]. DP-IV is upregulated in a numberof autoimmune diseases including rheumatoid arthritis, multiplesclerosis, Graves' disease, and Hashimoto's thyroiditis (ImmunologyToday 20: 367-375 (1999)).

-   HIV Infection: DP-IV inhibition may be useful for the treatment or    prevention of HIV infection or AIDS because a number of chemokines    which inhibit HIV cell entry are potential substrates for DP-IV    (Immunology Today 20: 367-375 (1999)). In the case of SDF-1alpha,    cleavage decreases antiviral activity (PNAS, 95: 6331-6 (1998)).    Thus, stabilization of SDF-1alpha through inhibition of DP-IV would    be expected to decrease HIV infectivity.-   Hematopoiesis: DP-IV inhibition may be useful for the treatment or    prevention of hematopiesis because DP-IV may be involved in    hematopoiesis. A DP-IV inhibitor, Val-Boro-Pro, stimulated    hematopoiesis in a mouse model of cyclophosphamide-induced    neutropenia (WO 99/56753).-   Neuronal Disorders: DP-IV inhibition may be useful for the treatment    or prevention of various neuronal or psychiatric disorders because a    number of peptides implicated in a variety of neuronal processes are    cleaved in vitro by DP-IV. A DP-IV inhibitor thus may have a    therapeutic benefit in the treatment of neuronal disorders.    Endomorphin-2, beta-casomorphin, and substance P have all been shown    to be in vitro substrates for DP-IV. In all cases, in vitro cleavage    is highly efficient, with k_(cat)/K_(m) about 10⁶ M⁻¹s⁻¹ or greater.    In an electric shock jump test model of analgesia in rats, a DP-IV    inhibitor showed a significant effect that was independent of the    presence of exogenous endomorphin-2 (Brain Research, 815: 278-286    (1999)). Neuroprotective and neuroregenerative effects of DP-IV    inhibitors were also evidenced by the inhibitors' ability to protect    motor neurons from excitotoxic cell death, to protect striatal    innervation of dopaminergic neurons when administered concurrently    with MPTP, and to promote recovery of striatal innervation density    when given in a therapeutic manner following MPTP treatment [see    Yong-Q. Wu, et al., “Neuroprotective Effects of Inhibitors of    Dipeptidyl Peptidase-IV In Vitro and In Vivo,” Int. Conf. On    Dipeptidyl Aminopeptidases: Basic Science and Clinical Applications,    Sep. 26-29, 2002 (Berlin, Germany)].-   Anxiety-   Rats naturally deficient in DP-IV have an anxiolytic phenotype (WO    02/34243; Karl et al., Physiol. Behav. 2003). DP-IV deficient mice    also have an anxiolytic phenotype using the Porsolt and light/dark    models. Thus DP-IV inhibitors may prove useful for treating anxiety    and related disorders.    Memory and Cognition-   GLP-1 agonists are active in models of learning (passive avoidance,    Morris water maze) and neuronal injury kainate-induced neuronal    apoptosis) as demonstrated by During et al. (Nature Med. 9:    1173-1179 (2003)). The results suggest a physiological role for    GLP-1 in learning and neuroprotection. Stabilization of GLP-1 by    DP-IV inhibitors are expected to show similar effects.-   Tumor Invasion and Metastasis: DP-IV inhibition may be useful for    the treatment or prevention of tumor invasion and metastasis because    an increase or decrease in expression of several ectopeptidases    including DP-IV has been observed during the transformation of    normal cells to a malignant phenotype (J. Exp. Med., 190: 301-305    (1999)). Up- or down-regulation of these proteins appears to be    tissue and cell-type specific. For example, increased CD26/DP-IV    expression has been observed on T cell lymphoma, T cell acute    lymphoblastic leukemia, cell-derived thyroid carcinomas, basal cell    carcinomas, and breast carcinomas. Thus, DP-IV inhibitors may have    utility in the treatment of such carcinomas.-   Benign Prostatic Hypertrophy: DP-IV inhibition may be useful for the    treatment of benign prostatic hypertrophy because increased DP-IV    activity was noted in prostate tissue from patients with BPH    (Eur. J. Clin. Chem. Clin. Biochem. 30: 333-338 (1992)).-   Sperm motility/male contraception: DP-IV inhibition may be useful    for the altering sperm motility and for male contraception because    in seminal fluid, prostatosomes, prostate derived organelles    important for sperm motility, possess very high levels of DP-IV    activity (Eur. J. Clin. Chem. Clin. Biochem., 30: 333-338 (1992)).-   Gingivitis: DP-IV inhibition may be useful for the treatment of    gingivitis because DP-IV activity was found in gingival crevicular    fluid and in some studies correlated with periodontal disease    severity (Arch. Oral Biol., 37: 167-173 (1992)).-   Osteoporosis: DP-IV inhibition may be useful for the treatment or    prevention of osteoporosis because GIP receptors are present in    osteoblasts.

The compounds of the present invention have utility in treating orpreventing one or more of the following conditions or diseases: (1)hyperglycemia, (2) low glucose tolerance, (3) insulin resistance, (4)obesity, (5) lipid disorders, (6) dyslipidemia, (7) hyperlipidemia, (8)hypertriglyceridemia, (9) hypercholesterolemia, (10) low HDL levels,(11) high LDL levels, (12) atherosclerosis and its sequelae, (13)vascular restenosis, (14) irritable bowel syndrome, (15) inflammatorybowel disease, including Crohn's disease and ulcerative colitis, (16)other inflammatory conditions, (17) pancreatitis, (18) abdominalobesity, (19) neurodegenerative disease, (20) retinopathy, (21)nephropathy, (22) neuropathy, (23) Syndrome X, (24) ovarianhyperandrogenism (polycystic ovarian syndrome), (25) Type II diabetes,(26) growth hormone deficiency, (27) neutropenia, (28) neuronaldisorders, (29) tumor metastasis, (30) benign prostatic hypertrophy,(32) gingivitis, (33) hypertension, (34) osteoporosis, and otherconditions that may be treated or prevented by inhibition of DP-IV.

The subject compounds are further useful in a method for the preventionor treatment of the aforementioned diseases, disorders and conditions incombination with other agents.

The compounds of the present invention may be used in combination withone or more other drugs in the treatment, prevention, suppression oramelioration of diseases or conditions for which compounds of Formula Ior the other drugs may have utility, where the combination of the drugstogether are safer or more effective than either drug alone. Such otherdrug(s) may be administered, by a route and in an amount commonly usedtherefor, contemporaneously or sequentially with a compound of FormulaI. When a compound of Formula I is used contemporaneously with one ormore other drugs, a pharmaceutical composition in unit dosage formcontaining such other drugs and the compound of Formula I is preferred.However, the combination therapy may also include therapies in which thecompound of Formula I and one or more other drugs are administered ondifferent overlapping schedules. It is also contemplated that when usedin combination with one or more other active ingredients, the compoundsof the present invention and the other active ingredients may be used inlower doses than when each is used singly. Accordingly, thepharmaceutical compositions of the present invention include those thatcontain one or more other active ingredients, in addition to a compoundof Formula I.

Examples of other active ingredients that may be administered incombination with a compound of Formula I, and either administeredseparately or in the same pharmaceutical composition, include, but arenot limited to:

(a) other dipeptidyl peptidase IV ODP-IV) inhibitors;

(b) insulin sensitizers including (i) PPARγ agonists such as theglitazones (e.g. troglitazone, pioglitazone, englitazone, MCC-555,rosiglitazone, balaglitazone, and the like) and other PPAR ligands,including PPARα/γ dual agonists, such as KRP-297 and muraglitazar, andPPARα agonists such as fenofibric acid derivatives (gemfibrozil,clofibrate, fenofibrate and bezafibrate), (ii) biguanides such asmetformin and phenformin, and (iii) protein tyrosine phosphatase-1B(PTP-1B) inhibitors;

(c) insulin or insulin mimetics;

(d) sulfonylureas and other insulin secretagogues, such as tolbutamideglyburide, glipizide, glimepiride, and meglitinides, such as nateglinideand repaglinide;

(e) α-glucosidase inhibitors (such as acarbose and miglitol);

(f) glucagon receptor antagonists such as those disclosed in WO98/04528, WO 99/01423, WO 00/39088, and WO 00/69810;

(g) GLP-1, GLP-1 mimetics, such as Exendin 4, and liraglutide, and GLP-1receptor agonists such as those disclosed in WO0/42026 and WO00/59887;

(h) GIP and GIP mimetics such as those disclosed in WO00/58360, and GPreceptor agonists;

(i) PACAP, PACAP mimetics, and PACAP receptor agonists such as thosedisclosed in WO 01/23420;

(j) cholesterol lowering agents such as (i) HMG-CoA reductase inhibitors(lovastatin, simvastatin, pravastatin, cerivastatin, fluvastatin,atorvastatin, itavastatin, and rosuvastatin, and other statins), (ii)sequestrants (cholestyramine, colestipol, and dialkylaminoalkylderivatives of a cross-linked dextran), (iii) nicotinyl alcohol,nicotinic acid or a salt thereof, (iv) PPARα agonists such as fenofibricacid derivatives (gemfibrozil, clofibrate, fenofibrate and bezafibrate),(v) PPARα/γ dual agonists, such as KRP-297, (vi) inhibitors ofcholesterol absorption, such as beta-sitosterol and ezetimibe, (vii)acyl CoA:cholesterol acyltransferase inhibitors, such as avasimibe, and(viii) anti-oxidants, such as probucol;

(k) PPARδ agonists, such as those disclosed in WO97/28149;

(l) antiobesity compounds such as fenfluramine, dexfenfluramine,phentermine, sibutramine, orlistat, neuropeptide Y₁ or Y₅ antagonists,CB1 receptor inverse agonists and antagonists, β₃ adrenergic receptoragonists, melanocortin-receptor agonists, in particular melanocortin-4receptor agonists, ghrelin antagonists, and melanin-concentratinghormone (MCH) receptor antagonists;

(m) ileal bile acid transporter inhibitors;

(n) agents intended for use in inflammatory conditions such as aspirin,non-steroidal anti-inflammatory drugs, glucocorticoids, azulfidine, andselective cyclooxygenase-2 inhibitors;

(o) antihypertensive agents such as ACE inhibitors (enalapril,lisinopril, captopril, quinapril, tandolapril), A-II receptor blockers(losartan, candesartan, irbesartan, valsartan, telmisartan, eprosartan),beta blockers and calcium channel blockers; and

(p) glucokinase activators (GKAs).

Dipeptidyl peptidase-IV inhibitors that can be combined with compoundsof structural formula I include those disclosed in WO 03/004498 (16 Jan.2003); WO 03/004496 (16 Jan. 2003); EP 1 258 476 (20 Nov. 2002); WO02/083128 (24 Oct. 2002); WO 02/062764 (15 Aug. 2002); WO 03/000250 (3Jan. 2003); WO 03/002530 (9 Jan. 2003); WO 03/002531 (9 Jan. 2003); WO03/002553 (9 Jan. 2003); WO 03/002593 (9 Jan. 2003); WO 03/000180 (3Jan. 2003); and WO 03/000181 (3 Jan. 2003). Specific DP-IV inhibitorcompounds include isoleucine thiazolidide; NVP-DPP728; P32/98; and LAF237.

Antiobesity compounds that can be combined with compounds of structuralformula I include fenfluramine, dexfenfluramine, phentermine,sibutramine, orlistat, neuropeptide Y₁ or Y₅ antagonists, cannabinoidCB1 receptor antagonists or inverse agonists, melanocortin receptoragonists, in particular, melanocortin-4 receptor agonists, ghrelinantagonists, and melanin-concentrating hormone (MCH) receptorantagonists. For a review of anti-obesity compounds that can be combinedwith compounds of structural formula I, see S. Chaki et al., “Recentadvances in feeding suppressing agents: potential therapeutic strategyfor the treatment of obesity,” Expert Opin. Ther. Patents, 11: 1677-1692(2001) and D. Spanswick and K. Lee, “Emerging antiobesity drugs,” ExpertOpin. Emerging Drugs, 8: 217-237 (2003).

Neuropeptide Y5 antagonists that can be combined with compounds ofstructural formula I include those disclosed in U.S. Pat. No. 6,335,345(1 Jan. 2002) and WO 01/14376 (1 Mar. 2001); and specific compoundsidentified as GW 59884A; GW 569180A; LY366377; and CGP-71683A.

Cannabinoid CB1 receptor antagonists that can be combined with compoundsof formula I include those disclosed in PCT Publication WO 03/007887;U.S. Pat. No. 5,624,941, such as rimonabant; PCT Publication WO02/076949, such as SLV-319; U.S. Pat. No. 6,028,084; PCT Publication WO98/41519; PCT Publication WO 00/10968; PCT Publication WO 99/02499; U.S.Pat. No. 5,532,237; and U.S. Pat. No. 5,292,736.

Melanocortin receptor agonists that can be combined with compounds ofstructural formula I include those disclosed in WO 03/009847 (6 Feb.2003); WO 02/068388 (6 Sep. 2002); WO 99/64002 (16 Dec. 1999); WO00/74679 (14 Dec. 2000); WO 01/70708 (27 Sep. 2001); and WO 01/70337 (27Sep. 2001) as well as those disclosed in J. D. Speake et al., “Recentadvances in the development of melanocortin-4 receptor agonists,” ExpertOpin. Ther. Patents, 12: 1631-1638 (2002).

The potential utility of safe and effective activators of glucokinase(GKAs) for the treatment of diabetes is discussed in J. Grimsby et al.,“Allosteric Activators of Glucokinase: Potential Role in DiabetesTherapy,” Science, 301: 370-373 (2003).

When a compound of the present invention is used contemporaneously withone or more other drugs, a pharmaceutical composition containing suchother drugs in addition to the compound of the present invention ispreferred. Accordingly, the pharmaceutical compositions of the presentinvention include those that also contain one or more other activeingredients, in addition to a compound of the present invention.

Likewise, compounds of the present invention may be used in combinationwith other drugs that are used in the treatment/prevention/suppressionor amelioration of the diseases or conditions for which compounds of thepresent invention are useful. Such other drugs may be administered, by aroute and in an amount commonly used therefor, contemporaneously orsequentially with a compound of the present invention. When a compoundof the present invention is used contemporaneously with one or moreother drugs, a pharmaceutical composition containing such other drugs inaddition to the compound of the present invention is preferred.Accordingly, the pharmaceutical compositions of the present inventioninclude those that also contain one or more other active ingredients, inaddition to a compound of the present invention.

The weight ratio of the compound of the compound of the presentinvention to the second active ingredient may be varied and will dependupon the effective dose of each ingredient. Generally, an effective doseof each will be used. Thus, for example, when a compound of the presentinvention is combined with another agent, the weight ratio of thecompound of the present invention to the other agent will generallyrange from about 1000:1 to about 1:1000, preferably about 200:1 to about1:200. Combinations of a compound of the present invention and otheractive ingredients will generally also be within the aforementionedrange, but in each case, an effective dose of each active ingredientshould be used.

In such combinations the compound of the present invention and otheractive agents may be administered separately or in conjunction. Inaddition, the administration of one element may be prior to, concurrentto, or subsequent to the administration of other agent(s).

The compounds of the present invention may be administered by oral,parenteral (e.g., intramuscular, intraperitoneal, intravenous, ICV,intracisternal injection or infusion, subcutaneous injection, orimplant), by inhalation spray, nasal, vaginal, rectal, sublingual, ortopical routes of administration and may be formulated, alone ortogether, in suitable dosage unit formulations containing conventionalnon-toxic pharmaceutically acceptable carriers, adjuvants and vehiclesappropriate for each route of administration. In addition to thetreatment of warm-blooded animals such as mice, rats, horses, cattle,sheep, dogs, cats, monkeys, etc., the compounds of the invention areeffective for use in humans.

The pharmaceutical compositions for the administration of the compoundsof this invention may conveniently be presented in dosage unit form andmay be prepared by any of the methods well known in the art of pharmacy.All methods include the step of bringing the active ingredient intoassociation with the carrier which constitutes one or more accessoryingredients. In general, the pharmaceutical compositions are prepared byuniformly and intimately bringing the active ingredient into associationwith a liquid carrier or a finely divided solid carrier or both, andthen, if necessary, shaping the product into the desired formulation. Inthe pharmaceutical composition the active object compound is included inan amount sufficient to produce the desired effect upon the process orcondition of diseases. As used herein, the term “composition” isintended to encompass a product comprising the specified ingredients inthe specified amounts, as well as any product which results, directly orindirectly, from combination of the specified ingredients in thespecified amounts.

The pharmaceutical compositions containing the active ingredient may bein a form suitable for oral use, for example, as tablets, troches,lozenges, aqueous or oily suspensions, dispersible powders or granules,emulsions, hard or soft capsules, or syrups or elixirs. Compositionsintended for oral use may be prepared according to any method known tothe art for the manufacture of pharmaceutical compositions and suchcompositions may contain one or more agents selected from the groupconsisting of sweetening agents, flavoring agents, coloring agents andpreserving agents in order to provide pharmaceutically elegant andpalatable preparations. Tablets contain the active ingredient inadmixture with non-toxic pharmaceutically acceptable excipients whichare suitable for the manufacture of tablets. These excipients may be forexample, inert diluents, such as calcium carbonate, sodium carbonate,lactose, calcium phosphate or sodium phosphate; granulating anddisintegrating agents, for example, corn starch, or alginic acid;binding agents, for example starch, gelatin or acacia, and lubricatingagents, for example magnesium stearate, stearic acid or talc. Thetablets may be uncoated or they may be coated by known techniques todelay disintegration and absorption in the gastrointestinal tract andthereby provide a sustained action over a longer period. For example, atime delay material such as glyceryl monostearate or glyceryl distearatemay be employed. They may also be coated by the techniques described inthe U.S. Pat. Nos. 4,256,108; 4,166,452; and 4,265,874 to form osmotictherapeutic tablets for control release.

Formulations for oral use may also be presented as hard gelatin capsuleswherein the active ingredient is mixed with an inert solid diluent, forexample, calcium carbonate, calcium phosphate or kaolin, or as softgelatin capsules wherein the active ingredient is mixed with water or anoil medium, for example peanut oil, liquid paraffin, or olive oil.

Aqueous suspensions contain the active materials in admixture withexcipients suitable for the manufacture of aqueous suspensions. Suchexcipients are suspending agents, for example sodiumcarboxymethylcellulose, methylcellulose, hydroxy-propylmethylcellulose,sodium alginate, polyvinyl-pyrrolidone, gum tragacanth and gum acacia;dispersing or wetting agents may be a naturally-occurring phosphatide,for example lecithin, or condensation products of an alkylene oxide withfatty acids, for example polyoxyethylene stearate, or condensationproducts of ethylene oxide with long chain aliphatic alcohols, forexample heptadecaethyleneoxycetanol, or condensation products ofethylene oxide with partial esters derived from fatty acids and ahexitol such as polyoxyethylene sorbitol monooleate, or condensationproducts of ethylene oxide with partial esters derived from fatty acidsand hexitol anhydrides, for example polyethylene sorbitan monooleate.The aqueous suspensions may also contain one or more preservatives, forexample ethyl, or n-propyl, p-hydroxybenzoate, one or more coloringagents, one or more flavoring agents, and one or more sweetening agents,such as sucrose or saccharin.

Oily suspensions may be formulated by suspending the active ingredientin a vegetable oil, for example arachis oil, olive oil, sesame oil orcoconut oil, or in a mineral oil such as liquid paraffin. The oilysuspensions may contain a thickening agent, for example beeswax, hardparaffin or cetyl alcohol. Sweetening agents such as those set forthabove, and flavoring agents may be added to provide a palatable oralpreparation. These compositions may be preserved by the addition of ananti-oxidant such as ascorbic acid.

Dispersible powders and granules suitable for preparation of an aqueoussuspension by the addition of water provide the active ingredient inadmixture with a dispersing or wetting agent, suspending agent and oneor more preservatives. Suitable dispersing or wetting agents andsuspending agents are exemplified by those already mentioned above.Additional excipients, for example sweetening, flavoring and coloringagents, may also be present.

The pharmaceutical compositions of the invention may also be in the formof oil-in-water emulsions. The oily phase may be a vegetable oil, forexample olive oil or arachis oil, or a mineral oil, for example liquidparaffin or mixtures of these. Suitable emulsifying agents may benaturally-occurring gums, for example gum acacia or gum tragacanth,naturally-occurring phosphatides, for example soy bean, lecithin, andesters or partial esters derived from fatty acids and hexitolanhydrides, for example sorbitan monooleate, and condensation productsof the said partial esters with ethylene oxide, for examplepolyoxyethylene sorbitan monooleate. The emulsions may also containsweetening and flavoring agents.

Syrups and elixirs may be formulated with sweetening agents, for exampleglycerol, propylene glycol, sorbitol or sucrose. Such formulations mayalso contain a demulcent, a preservative and flavoring and coloringagents.

The pharmaceutical compositions may be in the form of a sterileinjectable aqueous or oleagenous suspension. This suspension may beformulated according to the known art using those suitable dispersing orwetting agents and suspending agents which have been mentioned above.The sterile injectable preparation may also be a sterile injectablesolution or suspension in a non-toxic parenterally-acceptable diluent orsolvent, for example as a solution in 1,3-butane diol. Among theacceptable vehicles and solvents that may be employed are water,Ringer's solution and isotonic sodium chloride solution. In addition,sterile, fixed oils are conventionally employed as a solvent orsuspending medium. For this purpose any bland fixed oil may be employedincluding synthetic mono- or diglycerides. In addition, fatty acids suchas oleic acid find use in the preparation of injectables.

The compounds of the present invention may also be administered in theform of suppositories for rectal administration of the drug. Thesecompositions can be prepared by mixing the drug with a suitablenon-irritating excipient which is solid at ordinary temperatures butliquid at the rectal temperature and will therefore melt in the rectumto release the drug. Such materials are cocoa butter and polyethyleneglycols.

For topical use, creams, ointments, jellies, solutions or suspensions,etc., containing the compounds of The present invention are employed.(For purposes of this application, topical application shall includemouth washes and gargles.)

The pharmaceutical composition and method of the present invention mayfurther comprise other therapeutically active compounds as noted hereinwhich are usually applied in the treatment of the above mentionedpathological conditions.

In the treatment or prevention of conditions which require inhibition ofdipeptidyl peptidase-IV enzyme activity an appropriate dosage level willgenerally be about 0.01 to 500 mg per kg patient body weight per daywhich can be administered in single or multiple doses. Preferably, thedosage level will be about 0.1 to about 250 mg/kg per day; morepreferably about 0.5 to about 100 mg/kg per day. A suitable dosage levelmay be about 0.01 to 250 mg/kg per day, about 0.05 to 100 mg/kg per day,or about 0.1 to 50 mg/kg per day. Within this range the dosage may be0.05 to 0.5, 0.5 to 5 or 5 to 50 mg/kg per day. For oral administration,the compositions are preferably provided in the form of tabletscontaining 1.0 to 1000 mg of the active ingredient, particularly 1.0,5.0, 10.0, 15.0. 20.0, 25.0, 50.0, 75.0, 100.0, 150.0, 200.0, 250.0,300.0, 400.0, 500.0, 600.0, 750.0, 800.0, 900.0, and 1000.0 mg of theactive ingredient for the symptomatic adjustment of the dosage to thepatient to be treated. The compounds may be administered on a regimen of1 to 4 times per day, preferably once or twice per day.

When treating or preventing diabetes mellitus and/or hyperglycemia orhypertriglyceridemia or other diseases for which compounds of thepresent invention are indicated, generally satisfactory results areobtained when the compounds of the present invention are administered ata daily dosage of from about 0.1 mg to about 100 mg per kilogram ofanimal body weight, preferably given as a single daily dose or individed doses two to six times a day, or in sustained release form. Formost large mammals, the total daily dosage is from about 1.0 mg to about1000 mg, preferably from about 1 mg to about 50 mg. In the case of a 70kg adult human, the total daily dose will generally be from about 7 mgto about 350 mg. This dosage regimen may be adjusted to provide theoptimal therapeutic response.

It will be understood, however, that the specific dose level andfrequency of dosage for any particular patient may be varied and willdepend upon a variety of factors including the activity of the specificcompound employed, the metabolic stability and length of action of thatcompound, the age, body weight, general health, sex, diet, mode and timeof administration, rate of excretion, drug combination, the severity ofthe particular condition, and the host undergoing therapy.

Several methods for preparing the compounds of this invention areillustrated in the following Schemes and Examples. Starting materialsare made according to procedures known in the art or as illustratedherein.

The compounds of the present invention can be prepared from beta aminoacid intermediates such as those of formula II and substitutedheterocyclic intermediates such as those of formula III, using standardpeptide coupling conditions followed by deprotection. The preparation ofthese intermediates is described in the following schemes.

where Ar, W, X, Y, Z, R⁷, R⁸, and R⁹ are as defined above and P is asuitable nitrogen protecting group such as tert-butoxycarbonyl,benzyloxycarbonyl, or 9-fluorenylmethoxy-carbonyl.

Compounds of formula II are commercially available, known in theliterature or may be conveniently prepared by a variety of methodsfamiliar to those skilled in the art. One common route is illustrated inScheme 1. Acid 1, which may be commercially available or readilyprepared from the corresponding amino acid by protection using, forexample, di-tert-butyl-dicarbonate (for P=Boc), carbobenzyloxy chloride(for P=Cbz), or N-(9-fluorenylmethoxiycarbonyloxy)succinimide (forP=Fmoc), is treated with isobutyl chloroformate and a base such astriethylamine or N,N-diisopropylethylamine, followed by diazomethane.The resultant diazoketone is then treated with silver benzoate in asolvent such as methanol or aqueous dioxane and may be subjected tosonication following the procedure of Sewald et al., Synthesis, 837(1997) in order to provide the beta amino acid II. As will be understoodby those skilled in the art, for the preparation of enantiomericallypure beta amino acids II, enantiomerically pure alpha amino acids 1 maybe used. Alternate routes to these compounds can be found in thefollowing reviews: E. Juaristi, Eizantioselective Synthesis of β-AminoAcids, Ed., Wiley-VCH, New York: 1997, Juaristi et al., AldrichimicaActa, 27, 3 (1994), Cole et al., Tetrahedron, 32, 9517 (1994).

Compounds III are commercially available, known in the literature or maybe conveniently prepared by a variety of methods familiar to thoseskilled in the art. One convenient method when W is CH, X and Y are CR¹and Z is N is shown in Scheme 2. Piperidinone 2, in which the nitrogenis protected, for example, as a trityl or benzyl derivative, is treatedwith piperidine, conveniently in the presence of magnesium sulfate in asolvent such as tetrahydrofuran, to provide the corresponding enamine 3,in some cases as a mixture of isomers. Treatment of 3 withethoxyvinylcarbonyl derivative 4 followed by ammonium acetate, typicallyat elevated temperature, gives the fused pyridine derivative 5. Thisreaction is particularly favored when R^(1a) is H or CO₂C₁₋₆ alkyl andwhen R^(1b) is CF₃ or C₁₋₆ alkyloxy. When R^(1b) is C₁₋₆ alkyloxy,compound 5 is isolated as the hydroxypyridine derivative wherein R^(1b)is OH. The protecting group may be removed by treatment with acid suchas hydrogen choride when the protecting group is trityl or by catalytichydrogenation when the protecting group is benzyl to give the desiredproduct IIIa.

As illustrated in Scheme 3, compound IIIb wherein W is N, X and Y areCR¹ and Z is CH may be prepared from N-protected piperidinone 6,following the route described above for the synthesis of IIIa.

Compound IIIc wherein W, X and Y are CR¹ and Z is N may be prepared asillustrated in Scheme 4. Hydroxypyridine 9 is brominated, for example bytreatment with bromine and sodium acetate in acetic acid, to givebromopyridine 10. Deprotonation of the alcohol with sodium hydridefollowed by metal-halogen exchange, conveniently by treatment withtert-butyllithium gives a dianion which is quenched withN,N-dimethylformamide to provide aldehyde 11. Conversion of the aldehydeto the nitrile under standard conditions, for example by treatment withhydroxylamine hydrochloride and sodium formate in formic acid, givesnitrile 12. Treatment with phosphorus oxychloride provideschloropyridine 13. Displacement of the chloride by treatment with thesodium salt of methyl tert-butyl malonate gives pyridine 14. Raneynickel reduction followed by ring closure provides fused pyridine 15.Ester hydrolysis with TFA and decarboxylation gives amide 16. Boranereduction provides the desired compound IIIc.

Compound IIId wherein W is CH, X is CR¹, Y is N and Z is C—OR (R=C₁₋₆alkyl) may be prepared as illustrated in Scheme 5. Hydropyridine 17 isbrominated, conveniently using N-bromosuccinimide in DMF, to providedibromopyridine 18. The hydroxy group is alkylated, for example bytreatment with an alkyl halide such as an alkyl iodide in the presenceof silver carbonate, to provide alkoxypyridine 19. Formylation isachieved by deprotonation with a base such as lithiumN,N-diisopropylamide followed by quenching with methyl formate toprovide aldehyde 20. The aldehyde is treated with a reducing agent suchas sodium borohydride, and then protected with a protecting group suchas tert-butyldimethylsilyl (TBS) using TBS chloride. Treatment of theresultant pyridine 21 with phenyllithium followed by quenching with aproton source such as citric acid provides monobromide 22. Allylation ofthe bromide may be achieved by treatment with allyltributyltin in thepresence of a catalyst such as tetrakis(triphenylphosphine) palladium.The allyl group is oxidized, for example using N-methylmorpholineN-oxide and osmium tetroxide in a polar solvent such as acetone/waterfollowed by sodium periodate to provide aldehyde 24. Reductive aminationusing a protected ammonia equivalent such as (diphenylmethyl)amine and areducing agent such as sodium triacetoxyborohydride provides amine 25.The diphenylmethyl group is removed by catalytic hydrogenation and theresultant primary amine protected, for example, as its BOC derivative,by treatment with di-tert-butyl dicarbonate. Deprotection of the silylether to the corresponding alcohol using a fluoride source such astetrabutylammonium fluoride provides pyridine 26. The alcohol is treatedwith an oxidizing agent such as sulfur trioxide-pyridine to give thecorresponding aldehyde. Deprotection of the amine using an acid such ashydrogen chloride and then internal reductive amination gives thedesired cyclized intermediate IIId.

Compounds IIIe wherein W is CH, X is N, Y is CR¹ and Z is N may beconveniently prepared as shown in Scheme 6. N-protected 4-piperidinone27 is treated with 1,1-dimethoxy-N,N-dimethylmethanamine in DMF atelevated temperature to give enamine 28, which in some cases may be amixture of isomers. Condensation of 28 with amidine 29 in the presenceof a base such as sodium ethoxide in ethanol provides pyrimidine 30.Deprotection, in the case of BOC, with an acid such as hydrogen chlorideor trifluoroacetic acid gives tetrahydropyridopyrimidine IIIe.

N-protected 4-piperidinone 27 and amidine 29 are commercially available,known in the literature or may be conveniently prepared by a variety ofmethods familiar to those skilled in the art. One convenient method forpreparation of amidine 29 is shown in Scheme 7. Nitrile 31, which itselfis commercially available, known in the literature, or convenientlyprepared by a variety of methods familiar to those skilled in the art,is treated with hydrogen chloride, conveniently as a solution indioxane, in ethanol to give imidate 32. Treatment with an ethanolicammonia solution provides amidine 29.

The preparation of intermediate IIIf wherein W is C—OH, X is N, Y is CR¹and Z is N is illustrated in Scheme 8. Ketoester 33 is treated withamidine 29 in the presence of a base such as sodium ethoxide in ethanolto provide tetrahydropyridopyridimine 34. Deprotection of the nitrogenusing catalytic hydrogenation, for example by treatment with hydrogen inthe presence of palladium on carbon, provides IIIf.

One convenient method for the synthesis of intermediate IIIg wherein Wis N, X is CR¹, Y is CR¹ and Z is N and wherein R⁷ is an akyl or arylgroup is illustrated in Scheme 9. Pyridopyrazine 35 is activated withphenyl chloroformate and treated with a Grignard reagent to provide,after reduction with hydrogen in the presence of a catalyst such as 10%palladium on carbon, tetrahydropyridopyrazine 36. Conversion of thephenylcarbamate to a BOC group is accomplished by treatment withpotassium tert-butoxide. Removal of the BOC, for example, usingmethanolic hydrogen chloride, provides the desired intermediate IIIg.

Scheme 10 shows the preparation of intermediate IIIh, wherein W is N, Xis N, Y is CH and Z is CH. Hydroxypyridine 37 is hydrogenated in thepresence of a catalyst such as rhodium on alumina and the resultantpiperidine derivative protected as its BOC derivative. The alcohol isoxidized to give ketone 38, conveniently using Swern conditions.Treatment with a strong base such as LDA followed by trapping of theresultant enolate with an oxaldehyde synthon such as cinnamaldehydeprovides hydroxyketone 39. Ozonolysis followed by treatment withhydrazine gives the N-protected tetrahydropyridopyridazine derivative,which is treated with an acid such as trifluoroacetic acid to giveintermediate IIIh.

Intermediate IIIj, wherein W is N, X is N, Y is CR¹, and Z is N, andintermediate IIIk, wherein W is N, X is CR¹, Y is N, and Z is N, areavailable as outlined in Scheme 11. Tetrahydropyridine 40 is protected,for example as its BOC derivative by treatment with di-tert-butyldicarbonate, and the olefin oxidized, conveniently by treatment withosmium tetroxide and potassium chlorate, to provide diol 41. The diolmay be oxidized to diketone 42 using Swern conditions. Treatment ofdiketone 42 with an appropriate amidrazone 43 gives a mixture of twotetrahydropyridotriazines. These may be separated, for example by usingflash chromatography or HPLC, to provide, after deprotection underacidic conditions, intermediates IIIj and IIIk.

One convenient method for the synthesis of intermediate IIIm wherein R⁸is CONR³R⁴ is shown in Scheme 12. BOC protected aminoacid 44, which iscommercially available, known in the literature, or readily prepared bya variety of methods known to those skilled in the art, is treated withan amine under standard peptide coupling conditions, for example usingEDC and HOBt. Deprotection under acidic conditions provides the desiredintermediates IIIm.

Intermediates II and III are coupled under standard peptide couplingconditions, for example, using1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1-hydroxybenzotriazole(EDC/HOBT) or O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate and 1-hydroxy-7-azabenzotriazole (HATU/HOAT) in asolvent such as N,N-dimethylformamide (DMF) or dichloromethane for 3 to48 hours at ambient temperature to provide Intermediate 45 as shown inScheme 13. In some cases, Intermediate III may be a salt, such as ahydrochloride or trifluoroacetic acid salt, and in these cases it isconvenient to add a base, generally N,N-diisopropylethylamine, to thecoupling reaction. The protecting group is then removed with, forexample, trifluoroacetic acid or methanolic hydrogen chloride in thecase of Boc to give the desired amine I. The product is purified fromunwanted side products, if necessary, by recrystallization, trituration,preparative thin layer chromatography, flash chromatography on silicagel, such as with a Biotage® apparatus, or HPLC. Compounds that arepurified by HPLC may be isolated as the corresponding salt. Purificationof intermediates is achieved in the same manner.

In some cases the product I, prepared as described in Scheme 13, may befurther modified, for example, by manipulation of substituents on Ar,R⁷, R⁸, R⁹, W, X, Y or Z. These manipulations may include, but are notlimited to, reduction, oxidation, alkylation, acylation, and hydrolysisreactions that are commonly known to those skilled in the art.

In some cases intermediates described in the above schemes may befurther modified before the sequences are completed, for example, bymanipulation of substituents on Ar, R⁷, R⁸, R⁹, W, X, Y or Z. Thesemanipulations may include, but are not limited to, reduction, oxidation,alkylation, acylation, and hydrolysis reactions that are commonly knownto those skilled in the art.

One such example is illustrated in Scheme 14 for the preparation ofintermediate IIIn wherein W is CH, X is CR¹, Y is Cl, and Z is N.Tetrahydropyridopyridimine 5a, prepared as described in Scheme 2, istreated with a chlorinating agent such as phenylphosphonic dichloride orphosphorus oxychloride, typically at elevated temperatures such as100-200° C., to give chloropyridine 46. Deprotection of the nitrogenusing 1-chloroethyl chloroformate provides IIIn.

Another such example is shown in Scheme 15. Deprotection of intermediate46, prepared as described in Scheme 14, using catalytic hydrogenation,for example by treatment with hydrogen in the presence of palladium oncarbon, provides IIIo, wherein W is CH, X is CR¹, Y is CH, and Z is N.

An additional example is provided in Scheme 16 for the preparation ofintermediate IIIp, wherein W is CH, X is C-heterocycle, Y is CR¹, and Zis N. Ester 5b, prepared as described in Scheme 2, is subjected tocatalytic hydrogenation conditions to remove the benzyl protectinggroup, and the nitrogen is reprotected, for example, as its BOCderivative using di-tert-butyl dicarbonate. Hydrolysis of the esterprovides acid 47. The acid is converted to the corresponding nitrile 48using standard conditions. Treatment with hydroxylamine hydrochloridefollowed by an anhydride provides, after deprotection under acidicconditions, intermediate IIIp. As will be understood by those skilled inthe art, a variety of heterocycles are readily available from acid 47and nitrile 48 using methods in the literature or known to those skilledin the art.

Scheme 17 illustrates the preparation of intermediate 45c, wherein X isC—NHSO₂R⁵. Intermediate 45a, prepared as described in Scheme 13, ishydrogenated in the presence of a catalyst such as Pearlman's catalystto provide amine 45b. Sulfonylation of the amine may be achieved bytreatment with a sulfonyl chloride in the presence of a base,conveniently pyridine, to give intermediate 45c. Intermediates 45b and45c may be deprotected as described in Scheme 13 to give the finalproduct I.

The modification of additional intermediates is illustrated in Scheme18. Intermediate 45d, prepared as described in Scheme 13 usingintermediate IIIb from Scheme 3, is treated with lithium hydroxide in anaqueous solvent mixture such as tetrahydrofuran/methanol/water toprovide acid 45e. The acid is coupled with an amine using standard aminebond forming conditions such as EDC/HOBt to provide intermediate 45f.Intermediates 45d, 45e, and 45f may all be deprotected as described inScheme 13 to provide final products I.

In some cases the order of carrying out the foregoing reaction schemesmay be varied to facilitate the reaction or to avoid unwanted reactionproducts. The following examples are provided so that the inventionmight be more fully understood. These examples are illustrative only andshould not be construed as limiting the invention in any way.

(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,5-difluorophenyl)butanoic acidStep A: (R,S)-N-(tert-Butoxycarbonyl)-2,5-difluorophenylalanine

To a solution of 0.5 g (2.49 mmol) of 2,5-difluoro-DL-phenylalanine in 5mL of tert-butanol were added sequentially 1.5 mL of 2N aqueous sodiumhydroxide solution and 543 mg of di-tert-butyl dicarbonate. The reactionwas stirred at ambient temperature for 16 h and diluted with ethylacetate. The organic phase was washed sequentially with 1N hydrochloricacid and brine, dried over magnesium sulfate and concentrated in vacuo.The crude material was purified by flash chromatography (silica gel,97:2:1 dichloromethane:methanol:acetic acid) to afford 671 mg of thetitle compound. LC/MS: 302 (M+1).

Step B:(R,S)-3-[(tert-Butoxycarbonyl)amino]-1-diazo-4-(2,5-difluoro-phenyl)butan-2-one

To a solution of 2.23 g (7.4 mmol) of(R,S)-N-(tert-butoxycarbonyl)-2,5-difluorophenylalanine in 100 mL ofdiethyl ether at 0° C. were added sequentially 1.37 mL (8.1 mmol) oftriethylamine and 0.931 mL (7.5 mmol) of isobutyl chloroformate and thereaction was stirred at this temperature for 15 min. A cooled etherealsolution of diazomethane was then added until the yellow color persistedand stirring was continued for a further 16 h. The excess diazomethanewas quenched by dropwise addition of acetic acid, and the reaction wasdiluted with ethyl acetate and washed sequentially with 5% hydrochloricacid, saturated aqueous sodium bicarbonate solution and brine, driedover magnesium sulfate and concentrated in vacuo. Purification by flashchromatography (silica gel, 4:1 hexane:ethyl acetate) afforded 1.5 g ofdiazoketone.

¹H NMR (500 MHz, CDCl₃) δ 7.03-6.95 (m, 1H, 6.95-6.88 (m, 2H), 5.43 (bs,1H), 5.18 (bs, 1H), 4.45 (bs, 1H), 3.19-3.12 (m, 1H), 2.97-2.80 (m, 1H),1.38 (s, 9H).

Step C:(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,5-difluorophenyl)butanoic acid

To a solution of 2.14 g (6.58 mmol) of(R,S)-3-[(tert-butoxycarbonyl)-amino]-1-diazo-4-(2,5-difluorophenyl)butan-2-onedissolved in 100 mL of methanol at −30° C. were added sequentially 3.3mL (19 mmol) of diisopropylethylamine and 302 mg (1.32 mmol) of silverbenzoate. The reaction was stirred for 90 min before diluting with ethylacetate and washing sequentially with 2N hydrochloric acid, saturatedaqueous sodium bicarbonate, and brine. The organic phase was dried overmagnesium sulfate, concentrated in vacuo and the enantiomers wereseparated by preparative chiral HPLC (Chiralpak AD column, 5% ethanol inhexanes) to give 550 mg of the desired (R)-enantiomer, which elutedfirst. This material was dissolved in 50 mL of a mixture oftetrahydrofuran:methanol:1N aqueous lithium hydroxide (3:1:1) andstirred at 50° C. for 4 h. The reaction was cooled, acidified with 5%dilute hydrochloric acid and extracted with ethyl acetate. The combinedorganic phases were washed with brine, dried over magnesium sulfate andconcentrated in vacuo to give 360 mg of the title compound as a whitefoamy solid.

¹H NMR (500 MHz, CDCl₃) δ 7.21 (m, 1H), 6.98 (m, 2H), 6.10 (bs, 1H),5.05 (m,1H), 4.21 (m, 1H), 2.98 (m, 2H), 2.60 (m, 2H), 1.38 (s, 9H).

(3R)-3-[(tert-Butoxycarbonyl)amino]-4-[2-fluoro-4-(trifluoromethyl)phenyl]-butanoicacid Step A:(2R,5S)-2,5-Dihydro-3,6-dimethoxy-2-(2′-fluoro-4′-(trifluoromethyl)benzyl)-5-isopropylpyrazine

To a solution of 3.32 g (18 mmol) of commercially available(2S)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine in 100 mL oftetrahydrofuran at −70° C. was added 12 mL (19 mmol) of a 1.6M solutionof butyllithium in hexanes. After stirring at this temperature for 20min, 5 g (19.5 mmol) of 2-fluoro-4-trifluoromethylbenzyl bromide in 20mL of tetrahydrofuran was added and stirring was continued for 3 hbefore warming the reaction to ambient temperature. The reaction wasquenched with water, concentrated in vacuo, and extracted with ethylacetate. The combined organic phase was washed with brine, dried, andconcentrated in vacuo. Purification by flash chromatography (silica gel,0-5% ethyl acetate in hexanes) afforded 5.5 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ 7.33-7.25 (m, 3H), 4.35-4.31 (m, 1H), 3.75 (s,3H), 3.65 (s, 3H), 3.60 (t, 1H, J=3.4 Hz), 3.33 (dd, 1H, J=4.6, 13.5Hz), 3.03 (dd, 1H, J=7, 13.5 Hz), 2.25-2.15 (m, 1H), 1.0 (d, 3H, J=7Hz), 0.66 (d, 3H, J=7 Hz).

Step B:(R)-N-(tert-Butoxycarbonyl)-2-fluoro-4-trifluoromethyl-phenylalaninemethyl ester

To a solution of 5.5 g (15 mmol) of(2R,5S)-2,5-dihydro-3,6-dimethoxy-2-(2′-fluoro-4′-(trifluoromethyl)benzyl)-5-isopropylpyrazinein 50 mL of a mixture of acetonitrile:dichloromethane (10:1) was added80 mL of 1N aqueous trifluoroacetic acid. The reaction was stirred for 6h and the organic solvents were removed in vacuo. Sodium carbonate wasadded until the solution was basic (>pH 8), and then the reaction wasdiluted with 100 mL of tetrahydrofuran and 10 g (46 mmol) ofdi-tert-butyl dicarbonate was added. The resultant slurry was stirredfor 16 h, concentrated in vacuo, and extracted with ethyl acetate. Thecombined organic phase was washed with brine, dried, and concentrated invacuo. Purification by flash chromatography (silica gel, 20% ethylacetate in hexanes) afforded 5.1 g of the title compound.

¹H NMR (500 MHz, CDCl₃) δ 7.38-7.28 (m, 3H), 5.10 (bd, 1H), 4.65-3.98(m, 1H), 3.76 (s, 3H), 3.32-3.25 (m, 1H), 3.13-3.05 (m, 1H), 1.40 (s,9H).

Step C:(R)-N-(tert-Butoxycarbonyl)-2-fluoro-4-trifluoromethyl)phenyl-alanine

A solution of 5.1 g (14 mmol) of(R,S)-N-(tert-butoxycarbonyl)-2-fluoro-4-trifluoromethyl)phenylalaninemethyl ester in 350 mL of a mixture of tetrahydrofuran: methanol:1Nlithium hydroxide (3:1:1) was stirred at 50° C. for 4 h. The reactionwas cooled, acidified with 5% hydrochloric acid and extracted with ethylacetate. The combined organic phases were washed with brine, dried overmagnesium sulfate and concentrated in vacuo to give 4.8 g of the titlecompound.

¹H NMR (500 MHz, CD₃OD) δ 7.45-7.38 (m, 3H), 4.44-4.40 (m, 1H),3.38-3.33 (m, 1H), 2.98 (dd, 1H, J=9.6, 13.5 Hz), 1.44 (s, 9H).

Step D:(3R)-3-[(tert-Butoxycarbonyl)amino]-4-[2-fluoro-4-(trifluoromethyl)-phenyl]-butanoicacid

To a solution of 3.4 g (9.7 mmol) of the product from Step C in 60 mL oftetrahydrofuran at 0° C. were added sequentially 2.3 mL (13 mmol) ofdiisopropylethylamine and 1.7 mL (13 mmol) of isobutyl chloroformate andthe reaction was stirred at this temperature for 30 min. A cooledethereal solution of diazomethane was then added until the yellow colorpersisted and stirring was continued for a further 16 h. The excessdiazomethane was quenched by dropwise addition of acetic acid, and thereaction was diluted with ethyl acetate and washed sequentially with 5%hydrochloric acid, saturated aqueous sodium bicarbonate solution andbrine, dried over magnesium sulfate and concentrated in vacuo.Purification by flash chromatography (silica gel, 9:1 hexane:ethylacetate) afforded 0.5 g of diazoketone. To a solution of 0.5 g (1.33mmol) of the diazoketone dissolved in 100 mL of methanol at 0° C. wereadded sequentially 0.7 mL (4 mmol) of diisopropylethylamine and 32 mg(0.13 mmol) of silver benzoate. The reaction was stirred for 2 h beforediluting with ethyl acetate and washing sequentially with 2Nhydrochloric acid, saturated aqueous sodium bicarbonate, and brine. Theorganic phase was dried over magnesium sulfate, concentrated in vacuoand dissolved in 50 mL of a mixture of tetrahydrofuran:methanol:1Naqueous lithium hydroxide (3:1:1) and stirred at 50° C. for 3 h. Thereaction was cooled, acidified with 5% hydrochloric acid and extractedwith ethyl acetate. The combined organic phases were washed with brine,dried over magnesium sulfate and concentrated in vacuo to give 410 mg ofthe title compound as a white foamy solid.

¹H NMR (500 MHz, CD₃OD): δ 7.47-7.33 (m, 3-H), 4.88 (bs, 1H), 4.26-3.98(m, 1H), 3.06-3.01 (m, 1H), 2.83-2.77 (m, 1H), 2.58-2.50 (m, 2H), 1.29(s, 9H).

(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,4,5-trifluorophenyl)butanoicacid Step A:(2S,5R)-2,5-Dihydro-3,6-dimethoxy-2-isopropyl-5-(2′,4′,5′trifluorobenzyl)pyrazine

The title compound (3.81 g) was prepared from 3.42 g (18.5 mmol) of(2S)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine and 5 g (22.3 mmol)of 2,4,5-trifluorobenzyl bromide using the procedure described forIntermediate 2, Step A.

¹H NMR (500 MHz, CDCl₃): δ 7.01 (m, 1H), 6.85 (m, 1H), 4.22 (m, 1H),3.78 (m, 3H), 3.64 (m, 3H), 3.61 (m, 1H), 3.20 (m, 1H), 2.98 (m, 1H),2.20 (m, 1H, 0.99 (d, 3H, J=8 Hz), 0.62 (d, 3H, J=8 Hz).

Step B: (R)-N-(tert-Butoxycarbonyl)-2,4,5-trifluorophenylalanine methylester

To a solution of 3.81 g (11.6 mmol) of(2S,5R)-2,5-dihydro-3,6-dimethoxy-2-isopropyl-5-(2′,4′,5′trifluorobenzyl)pyrazinein 20 mL of acetonitrile was added 20 mL of 2N hydrochloric acid. Thereaction was stirred for 72 h and concentrated in vacuo. The residue wasdissolved in 30 mL of dichloromethane and 10 mL (72 mmol) oftriethylamine and 9.68 g (44.8 mmol) of di-tert-butyl dicarbonate wereadded. The reaction was stirred for 16 h, diluted with ethyl acetate andwashed sequentially with 1N hydrochloric acid and brine. The organicphase was dried over sodium sulfate, concentrated in vacuo and purifiedby flash chromatography (silica gel, 9:1 hexanes:ethyl acetate) toafford 2.41 g of the title compound.

¹H NMR (500 MHz, CDCl₃): δ 6.99 (m, 1H), 6.94 (m, 1H), 5.08 (m, 1H),4.58 (m, 1H), 3.78 (m, 3H), 3.19 (m, 1H), 3.01 (m, 1H), 1.41 (s, 9H).

Step C: (R)-N-(tert-Butoxycarbonyl)-2,4,5-trifluorophenylalanine

The title compound (2.01 g) was prepared from 2.41 g (7.5 mmol) of(R)-N-(tert-butoxycarbonyl)-2,4,5-trifluorophenylalanine methyl esterusing the procedure described for Intermediate 2, Step C. LC/MS: 220.9(M+1-BOC).

Step D:(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,4,5-trifluorophenyl)-butanoicacid

To a solution of 0.37 g (1.16 mmol) of(R)-N-(1,1-dimethylethoxy-carbonyl)-2,4,5-trifluorophenylalanine in 10mL of diethyl ether at −20° C. were added sequentially 0.193 mL (1.3mmol) of triethylamine and 0.18 mL (1.3 mmol) of isobutyl chloroformate,and the reaction was stirred at this temperature for 15 min. A cooledethereal solution of diazomethane was then added until the yellow colorpersisted and stirring was continued for a further 1 h. The excessdiazomethane was quenched by dropwise addition of acetic acid, and thereaction was diluted with ethyl acetate and washed sequentially withsaturated aqueous sodium bicarbonate solution and brine, dried overmagnesium sulfate and concentrated in vacuo. Purification by flashchromatography (silica gel, 3:1 hexane:ethyl acetate) afforded 0.36 g ofdiazoketone. To a solution of 0.35 g (1.15 mmol) of the diazoketonedissolved in 12 mL of 1,4-dioxane:water (5:1) was added 26 mg (0.113mmol) of silver benzoate. The resultant solution was sonicated for 2 hbefore diluting with ethyl acetate and washing sequentially with 1Nhydrochloric acid and brine, drying over magnesium sulfate andconcentrating in vacuo. Purification by flash chromatography (silicagel, 97:2:1 dichloromethane:methanol:acetic acid) afforded 401 mg of thetitle compound.

¹H NMR (500 MHz, CDCl₃) δ 7.06 (m, 1H), 6.95 (m, 1H), 5.06 (bs, 1H),4.18 (m, 1H), 2.98 (m, 2H), 2.61 (m, 2H), 1.39 (s, 9H).

(3R)-4-(2-Bromo-4,5-difluorophenyl)-3-[(tert-butoxycarbonyl)amino]-butanoicacid

To a solution of 2.4 g (10 mmol) of 2-bromo-4,5-difluorobenzoic acid[prepared according to the procedure of Braish et al., Syn. Comm.,3067-3074 (1992)] in 75 mL of tetrahydrofuran was added 2.43 g (15 mmol)of carbonyldiimidazole. The solution was heated under reflux for 3.5 h,cooled to ambient temperature and 0.38 g (10 mmol) of sodium borohydridein 15 mL of water was added. The reaction was stirred for 10 min andpartitioned between ethyl acetate and 10% aqueous sodium bicarbonatesolution. The organic layer was washed twice with warm water, brine,dried over magnesium sulfate, and concentrated in vacuo. Purification byflash chromatography (silica gel, 4:1 hexane:ethyl acetate) afforded 1.9g of 2-bromo-4,5-difluorobenzyl alcohol. To a solution of 1.9 g (8.4mmol) of 2-bromo-4,5-difluorobenzyl alcohol in 30 mL of dichloromethaneat 0° C. was added 3.4 g (10 mmol) of carbon tetrabromide and 2.7 g (10mmol) of triphenylphosphine. The reaction was stirred for 2 h at thistemperature, the solvent was removed in vacuo and the residue stirredwith 100 mL of diethyl ether. The solution was filtered, concentrated invacuo, and purified by flash chromatography (silica gel, 20:1hexane:ethyl acetate) to afford 2.9 g of 2-bromo-4,5-difluorobenzylbromide contaminated with carbon tetrabromide which was used withoutfurther purification. Using the procedures outlined for the preparationof Intermediates 2-4, the benzyl bromide derivative was converted to thetitle compound.

LC/MS: 394 and 396 (M+1).

Essentially following the procedures outlined for the preparation ofIntermediates 1-4, the Intermediates in Table 1 were prepared.

TABLE 1

Intermediate R³ Selected ¹H NMR data (CD₃OD) 5 2-F,4-Cl,5-F 7.11 (dd, 1H, J = 8.9, 6.4 Hz), 7.03 (dd, 1 H, J = 9.0, 6.6) 6 2-F,5-Cl 7.27 (dd, 1H, J = 6.4, 2.5 Hz), 7.21 (m. 1 H), 7.03 (t, 1 H, J = 9.2 Hz) 72-Me,5-Cl 7.16 (d, 1 H, J = 1.8 Hz), 7.11-7.07 (m, 2 H), 2.34 (s, 3 H) 82-Cl,5-Cl 7.34 (d, 1 H, J = 9.0), 7.33 (d, 1 H, J = 2.1 Hz), 7.21 (dd, 1H, J = 8.5, 2.5 Hz) 9 2-F,3-Cl,6-F 7.35 (td, 1 H, J = 8.5, 5.8 Hz), 6.95(t, 1 H, J = 8.5 Hz) 10 3-Cl,4-F 7.33 (d, 1 H, J = 6.9 Hz), 7.19-7.11(m, 2 H) 11 2-F,3-F,6-F 7.18-7.12 (m, 1 H), 6.91 (m, 1 H) 12 2-F,4-F,6-F6.81 (t, 2 H, J = 8.4 Hz) 13 2-OCH₂Ph,5-F 7.49 (d, 2 H, J = 7.6 Hz),7.38 (t, 2 H, J = 7.3 Hz), 7.30 (t, 1 H, J = 7.3 Hz), 6.96-6.89 (m, 3H), 5.11 (d, 1 H, J = 11.7 Hz), 5.08 (d, 1 H, J = 11.9 Hz)

(3S)-3-(Pyrrolidin-1-ylcarbonyl)-1,2,3,4-tetrahydroisoquinoline

To a solution ofN-(tert-butoxycarbonyl)-(3S)-1,2,3,4-tetrahydro-isoquinoline-3-carboxylicacid (Boc-TIC-OH; 5.55 g, 20 mmol) in 200 mL of dichloromethane wasadded (1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride(EDC, 4.03 g, 21 mmol), 1-hydroxybenzotriazole (HOBt; 2.85 g, 21 mmol)and N,N-diisopropylethylamine (4.4 mL, 25 mmol). After 10 min,pyrrolidine (1.8 mL, 21 mmol) was added, and the resultant solution wasstirred at room temperature for 18 h. Additional dichloromethane (200mL) was added, and the solution was washed sequentially with ice-cold 5%hydrochloric acid, saturated aqueous sodium bicarbonate solution, andsaturated brine. The organic phase was dried over sodium sulfate andconcentrated under reduced pressure to afford a pale yellow solid.Purification by flash chromatography (silica gel; 45% ethylacetate-hexanes as eluant) afforded the BOC-protected intermediate (6.05g) as an off-white solid, which was dissolved in 100 mL ofdichloromethane, cooled in an ice-water bath and treated dropwise with40 mL of trifluoroacetic acid. The solution was warmed to roomtemperature and, after 1.5 h, concentrated under reduced pressure. Theresultant crude oil was partitioned between dichloromethane and 1Naqueous sodium hydroxide solution, and the aqueous layer was furtherextracted with dichloromethane. The combined organic extracts werewashed with saturated brine, dried over sodium sulfate and concentratedunder reduced pressure to afford a light yellow solid, which wasrecrystallized from ethyl acetate-hexanes to provide the title compoundas a white powder. LC/MS: 231.1 (M+1).

(3S)-3-(Piperidin-1-ylcarbonyl)-1,2,3,4-tetrahydroisoquinoline

Following a procedure similar to that described for Intermediate 14,treatment of Boc-TIC-OH with EDC, HOBt, N,N-diisopropylethylamine andpiperidine, followed by deprotection using trifluoroacetic acid,afforded the title compound as a white foam. LC/MS: 245.2 (M+1).

Methyl[4-[[[(3S)-1,2,3,4-tetrahydroisoquinolin-3-ylcarbonyl]amino]methyl]phenyl]acetate,trifluoroacetic acid

To a solution ofN-(tert-butoxycarbonyl)-(3S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylicacid (Boc-TIC-OH; 111 mg, 0.4 mmol) in 2.0 mL of dichloromethane wereadded 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride(EDC; 84 mg, 0.44 mmol) and N,N-diisopropylethylamlne (0.154 mL, 0.88mmol). After 10 min, methyl 4-(aminomethyl)phenylacetate hydrochloride(95 mg, 0.44 mmol) was added, and the resultant solution was stirred atroom temperature for 24 h. Additional dichloromethane (6 mL) was added,and the solution was washed sequentially with ice-cold 5% hydrochloricacid, saturated aqueous sodium bicarbonate solution, and saturatedbrine. The organic phase was dried over sodium sulfate and concentratedunder reduced pressure to a pale yellow oil. Purification by flashchromatography (silica gel; 35-50% ethyl acetate/hexanes step gradient)afforded the BOC-protected intermediate (68 mg) as a clear oil, whichwas dissolved in 4 mL of dichloromethane and treated with 2 mL oftrifluoroacetic acid. The solution was stirred at room temperature for 1h and was then concentrated under reduced pressure to afford the titlecompound as a white powder. LC/MS: 339.2 (M+1).

Benzyl4-[(3S)-1,2,3,4-tetrahydroisoguinolin-3-ylcarbonyl]piperazine-1-carboxylate,trifluoroacetic acid salt

Following a procedure similar to that described for Intermediate 14,treatment of Boc-TIC-OH with EDC, HOBt, N,N-diisopropylethylamine andbenzyl 1-piperazinecarboxylate, followed by deprotection usingtrifluoroacetic acid, afforded the title compound as a white solid.LC/MS: 380.1 (M+1).

Ethyl 2-hydroxy-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate,acetic acid salt Step A: Ethyl6-benzyl-2-hydroxy-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate

A solution of 1-benzyl-4-piperidone (20 g, 106 mmol) and pyrrolidine(11.3 g, 159 mmol) in 300 mL of toluene was warmed at reflux for 18 hwith azeotropic distillation of the water formed. The yellow solutionwas then concentrated under reduced pressure, and the resultant orangeoil was dissolved in 200 mL of anhydrous 1,4-dioxane. To this solutionwas added 24 mL of diethyl ethoxymethylenemalonate under ice cooling.The mixture was then warmed at reflux temperature for 6 h, and wasallowed to cool to room temperature overnight. Ammonium acetate (14.5 g)was added, and the reaction mixture was heated at reflux temperature for1 h. The mixture was cooled to room temperature and was concentratedunder reduced pressure to afford a red oil, which was triturated withether. The resultant precipitate was collected and dried in vacuo toafford the title compound as a yellow powder.

Step B: Ethyl2-hydroxy-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate, aceticacid salt

A mixture of the product (0.060 g, 0.19 mmol) from Step A above and 10%palladium on carbon (0.010 g) in 20 mL of glacial acetic was placedunder a balloon of hydrogen and stirred overnight. The reaction mixturewas filtered through a pad of Celite, and the filtrate was concentratedunder reduced pressure to afford the title compound. LC/MS: 223 (M+1)

Ethyl 2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate,hydrochloride Step A: Ethyl6-benzyl-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate,hydrochloride

A mixture of the product from Intermediate 18, Step A (1.0 g, 3.2 mmol)and phenylphosphonic dichloride (1 mL) was warmed to 150° C. After 1 h,the mixture was cooled and to the dark brown mixture was addeddiisopropyl ether. The precipitated crystals were collected byfiltration and suspended in chloroform. The mixture was neutralized bydropwise addition of saturated aqueous sodium bicarbonate solution. Theorganic layer was separated, dried over sodium sulfate and concentratedunder reduced pressure. The residue was purified by flash chromatography(silica gel; 15% ethyl acetate/hexanes as eluant) to afford the titlecompound.

Step B: Ethyl2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate,hydrochloride salt

A solution of the product from Step A above (0.095 mg, 0.287 mmol) in 10mL of dichloromethane was treated with 1-chloroethyl chloroformate(0.050 g; 0.344 mmol), and the mixture was warmed at reflux temperatureovernight. The reaction was concentrated under reduced pressure toafford a yellow oil, which was dissolved in 10 mL of methanol. Thesolution was heated at 40° C. for 2 h, cooled to room temperature andconcentrated in vacuo. To the yellow solid was added diisopropyl ether.The pale yellow crystals were collected by filtration and recrystallizedfrom ethanol to afford the title compound. LC/MS: 240.0 (M+1)

Ethyl2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate,hydrochloride salt Step A:1-Benzyl-4-pyrrolidino-1,2,5,6-tetrahydropyridine

A solution of N-benzyl piperidone (20.0 g, 53 mmol) and pyrrolidine(14.0 mL, 80 mmol) in 300 mL of toluene was warmed at reflux overnightwith azeotropic removal of water. The reaction mixture was then cooledand concentrated under reduced pressure. The resultant dark oil wasdissolved in 200 mL of ether, dried over magnesium sulfate, filtered andconcentrated under reduced pressure.

Step B: Ethyl6-benzyl-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthridine-3-carboxylate

A solution of the crude enamine (2.67 g, 10.6 mmol) from Step A above in30 mL of dry 1,4-dioxane was cooled to approximately 10° C. and ethyl2-(ethoxymethylene)-4,4,4-trifluoro-3-oxobutyrate (2.3 mL, 11.7 mmol)was added dropwise. The resultant orange solution was allowed to warm toroom temperature overnight. Ammonium acetate (1.78 g) was added to theblood-red solution, and the mixture was heated at reflux for 2 h, cooledto room temperature and concentrated under reduced pressure. The residuewas partitioned between ether and water, and the ether layer was washedwith saturated brine, dried over magnesium sulfate and concentrated to ared oil. Purification by flash chromatography (silica gel; 12% ethylacetate/hexanes as eluant) followed by preparative TLC (silica gel; 15%ethyl acetate/hexanes as eluant) afforded the title compound as a lightyellow oil. LC/MS 365.2 (M+1).

Step C: Ethyl2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate,hydrochloride salt

A solution of the product (140 mg, 0.385 mmol) from Step B in 1.5 mL ofdry dichloromethane was treated with 1-chloroethyl chloroformate (0.050mL, 0.46 mmol). The reaction mixture was warmed to 45° C. After 20 h,the solution was cooled to room temperature and concentrated under astream of nitrogen. The resultant residue was dissolved in 3 mL ofmethanol and the solution was warmed at 40° C. for 2.5 h. The resultantsolution was cooled and concentrated under a stream of nitrogen, and theresidue was triturated with 4 mL of ethyl acetate. The solid precipitatewas collected and dried in vacuo to afford the title compound as a whitecrystalline solid. LC/MS 275.0 (M+1).

Ethyl 5,6,7,8-Tetrahydro-1,6-naphthyridine-3-carboxylate, acetic acidsalt

A mixture of Intermediate 19 (3.70 g, 11.0 mmol) and 10% palladium oncarbon (0.37 g) in glacial acetic acid (10 mL) was placed under aballoon of hydrogen and stirred at room temperature overnight. Thereaction mixture was filtered through a pad of Celite, and the filtratewas concentrated under reduced pressure. Trituration with ether affordedthe title compound as a white powder. LC/MS: 207 (M+1).

3-(Trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine, hydrochlorideStep A: 3-Bromo-2-hydroxy-5-trifluoromethylpyridine

To a solution of 5-trifluoromethyl-2-pyridinol (51 g, 310 mmol) andsodium acetate (26.2 g, 319 mmol) in glacial acetic acid (200 mL) wasadded bromine (16.7 mL, 325 mmol) and the resultant mixture was heatedat 80° C. for 2.5 h. The reaction was allowed to cool to roomtemperature and then was evaporated under reduced pressure. The residuewas neutralized with saturated aqueous sodium bicarbonate solution andextracted with 3 portions of ethyl acetate. The organic extracts werecombined, dried over magnesium sulfate and concentrated under reducedpressure to afford the title compound. ¹H NMR (400 MHz, CDCl₃) δ 8.04(d, J=2.6 Hz, 1H), 7.89 (m, 1H).

Step B: 3-Formyl-2-hydroxy-5-trifluoromethylpyridine

Under nitrogen, the compound from Step A above (48.8 g, 202 mmol) wasadded in small portions to a suspension of sodium hydride (8.9 g, 220mmol) in anhydrous tetrahydrofuran (500 mL). After complete addition ofthe intermediate, the reaction mixture was cooled to −78° C. and treatedwith tert-butyllithium (260 mL, 444 mmol) added dropwise via syringe.After stirring for 5 min, N,N-dimethylformamide (50 mL, 707 mmol) wasadded slowly, maintaining the temperature below −50° C. The resultantmixture was allowed to slowly warm to room temperature over 10 h. Themixture was quenched with 2N hydrochloric acid and then diluted withethyl acetate (1000 mL). The organic layer was separated, washed withsaturated brine, dried over magnesium sulfate and evaporated in vacuo.The desired product was precipitated out of a mixture of ethyl acetateand hexanes and filtered to yield a light brown solid.

¹H NMR (500 MHz, CD₃OD) δ 10.13 (s, 1H), 8.21 (s, 2H).

Step C: 3-Cyano-2-hydroxy-5-trifluoromethylpyridine

A mixture of the compound from Step B above (18 g, 95 mmol), sodiumformate (7.1 g, 110 mmol), hydroxylamine hydrochloride (7.3 g, 110mmol), and formic acid (150 mL) was stirred at room temperature for 2 hand then heated to reflux overnight. The reaction mixture was cooled,allowed to stand at room temperature for 7 d, poured into water andextracted with three portions of ethyl acetate. The combined organiclayers were washed sequentially with two portions of water, saturatedaqueous sodium bicarbonate solution and brine, dried over sodium sulfateand concentrated in vacuo to yield the desired product as a brownpowder. ¹H NMR (400 MHz, CD₃OD) δ 8.37 (d, J=2.7 Hz, 1H), 8.19 (q, J=0.7Hz, 0.3 Hz, 1H).

Step D: 2-Chloro-3-cyano-5-trifluoromethylpyridine

To a mixture of phosphorous oxychloride (13.4 mL, 144 mmol) andquinoline (8.7 mL, 73 mmol) was added the product from Step C above(24.6 g, 131 mmol) and the resultant mixture was heated to reflux for 3h. The reaction was cooled to 100° C. before water (70 mL) was slowlyadded. The mixture was further cooled to room temperature andneutralized by the cautious addition of saturated aqueous sodiumbicarbonate solution. The aqueous layer was extracted with threeportions of ethyl acetate and the organic layers were combined, driedover magnesium sulfate and concentrated in vacuo. The crude product waspurified by flash chromatography to afford the desired compound. ¹H NMR(500 MHz, CDCl₃) δ 8.88 (d, J=2.0 Hz, 1H), 8.26 (d, J=2.5 Hz, 1H).

Step E: tert-Butyl methyl2-[3-cyano-5-(trifluoromethyl)pyridin-2-yl]malonate

To a suspension of sodium hydride (7.8 g, 200 mmol) in tetrahydrofuran(100 mL) under nitrogen was added dropwise a solution of tert-butylmethyl malonate (20 mL, 120 mmol) in anhydrous tetrahydrofuran (100 mL)via syringe. The reaction mixture was stirred for 0.5 h before asolution of the intermediate prepared in Step D above (20.1 g, 97.6mmol) in tetrahydrofuran (200 mL) was added slowly via syringe. Thereaction was stirred at room temperature overnight, then quenched with asaturated solution of ammonium chloride. The organic layer was separatedand the aqueous layer was extracted with three portions of ethylacetate. The combined organic layers were washed with water, dried oversodium sulfate and concentrated in vacuo. Flash chromatography affordedthe title compound. ¹H NMR (500 MHz, CDCl₃) δ 9.03 (d, J=1.5 Hz, 1H),8.25 (d, J=2.0 Hz, 1H), 5.25 (s, 1H), 3.86 (s, 3M), 1.52 (s, 9H).

Step F: tert-Butyl7-oxo-3-(trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-8-carboxylate

A suspension of Raney nickel (1 g) and the product from Step E above(18.2 g, 52.9 mmol) in ethanol (130 mL) was placed on a Parr shakerapparatus and hydrogenated at 40 psi hydrogen overnight. The suspensionwas filtered through Celite and the filtrate was evaporated in vacuo toafford the title compound. ¹H NMR (500 MHz, CDCl₃) δ 8.83 (s, 1H), 7.89(s, 1H), 7.82 (s, 1H), 4.83 (d, J=16 Hz, 1H), 4.72 (s, 1H), 4.49 (d,J=16 Hz, 1H), 1.45 (s, 9H).

Step G: 3-(Trifluoromethyl)-5,8-dihydro-1,6-naphthyridin-7(6H)-one

To a mixture of the product from Step F above (16 g, 51 mmol) indichloromethane (60 mL) was added trifluoroacetic acid (30 mL) and theresultant solution was stirred at room temperature for 0.5 h. Thesolution was evaporated under reduced pressure and the residue wasdissolved in dichloromethane. The mixture was neutralized by the slowaddition of a solution of saturated sodium bicarbonate and the organiclayer was removed. The aqueous layer was extracted with four portions ofdichloromethane and the combined organic layers were dried over sodiumsulfate and concentrated under reduced pressure to afford the titlecompound. ¹H NMR (400 MHz, CDCl₃) δ 8.81 (s, 1H), 7.78 (s, 1H), 7.30 (s,1H), 4.63 (s, 2H), 3.90 (s, 2H).

Step H:6-(tert-Butoxycarbonyl)-3-(trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine

To a solution of the product from Step G above (18.0 g, 83.3 mmol) intetrahydrofuran (50 mL) was added 1.0M borane in tetrahydrofuran (417mL, 420 mmol) and the resultant solution was stirred at room temperatureovernight. The solution was evaporated under reduced pressure and theresidue was treated with 1% methanolic hydrogen chloride solution. Theresultant mixture was heated at 50° C. overnight to break down theborane complex. Treatment with methanolic hydrogen chloride was repeatedtwice to insure that the borane complex was removed. A solution of thecrude product and N,N-diisopropylethylamine (43 mL, 250 mmol) indichloromethane was treated with di-tert-butyl dicarbonate (36.4 g, 167mmol) and the resultant mixture was stirred at room temperatureovernight. The solution was washed sequentially with saturated sodiumbicarbonate solution, water, and saturated brine. The aqueous layerswere combined and extracted with two portions of dichloromethane. Thecombined organic layers were then dried over sodium sulfate andconcentrated under reduced pressure. The crude product was purified byflash chromatography and medium-pressure liquid chromatography (MPLC) toafford the title compound as a yellow solid. ¹H NMR (500MHz, CDCl₃) δ8.69 (s, 1H), 7.66 (s, 1H), 4.67 (s, 2H), 3.79 (t, J=6.0 Hz, 2H), 3.08(t, J=6.0 Hz, 2H), 1.51 (s, 9H).

Step I: 3-(Trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridinehydrochloride

The product described in Step H above (11.89 g) was treated with asolution of 4N hydrogen chloride in 1,4-dioxane. The solution wasstirred at room temperature for 2 h and then concentrated in vacuo toafford the title compound as a yellow powder. LC/MS 203.0 (M+H).

3-[5-(Trifluoromethyl)-1,2,4-oxadiazol-3-yl]-5,6,7,8-tetrahydro-1,6-naphthyridine,trifluoroacetic acid salt Step A: Ethyl6-(tert-butoxycarbonyl)-2-chloro-5,6,7,8-tetrahydro-1,6-naphthyridine-3-carboxylate

To an ice-cold solution of Intermediate 21 (1.07 g, 4.0 mmol) in 10 mLof dichloromethane was added di-tert-butyl dicarbonate (0.88 g, 4.0mmol) and N,N-diisopropylethylamine (0.7 mL, 4.0 mmol), and the reactionmixture was allowed to warm to room temperature overnight. The mixturewas diluted with ethyl acetate and was washed sequentially with ice-cold1M hydrochloric acid, saturated aqueous sodium bicarbonate solution andsaturated brine, dried over magnesium sulfate and concentrated underreduced pressure. The residue was purified by flash chromatography(silica gel; 10-30% ethyl acetate/hexanes gradient elution) to affordthe title compound as a white solid.

Step B:6-(tert-Butoxycarbonyl)-3-cyano-5,6,7,8-tetrahydro-1,6-naphthyridine

To a solution of the product from Step A above in 6 mL of 3:2:1tetrahydrofuran/methanol/water was added lithium hydroxide monohydrate(0.23 g, 5.58 mmol). The mixture was allowed to stir overnight and thevolatiles were removed under reduced pressure. Additional water wasadded, and the solution was acidified with citric acid monohydrate. Theresultant precipitate was collected, washed with water, and dried invacuo. To an ice-cold solution of this intermediate (1.0 g, 3.6 mmol) in32 mL of pyridine was added methanesulfonyl chloride (0.41 g, 3.6 mmol)dropwise, and the resultant mixture was allowed to stir for one hour.Dry ammonia gas was bubbled into the reaction mixture for 2 minutes. Theexcess ammonia was then removed under reduced pressure, and the solutionwas cooled again in ice and treated with methanesulfonyl chloride (3.43g, 30.0 mmol). The resultant mixture was allowed to warm to roomtemperature overnight. The reaction was concentrated under reducedpressure, and the residue was partitioned between ethyl acetate and 1Nhydrochloric acid. The product was extracted with ethyl acetate, and thecombined extracts were dried over magnesium sulfate and concentratedunder reduced pressure. The resultant crystalline solid was trituratedwith ether, and the precipitate was collected to afford the titlecompound as a light orange powder.

Step C:3-[5-(Trifluoromethyl)-1,2,4-oxadiazol-3-yl]-5,6,7,8-tetrahydro-1,6-naphthyridine,trifluoroacetic acid salt

To a solution of the compound from Step B above in 7 mL of absoluteethanol (0.2 g, 0.77 mmol) was added hydroxylamine hydrochloride (0.067g, 0.97 mmol), and sodium carbonate (0.1 g, 0.97 mmol). The reaction waswarmed to reflux and, after 18 h, cooled to room temperature andconcentrated under reduced pressure. To this crude intermediate wereadded pyridine (2.0 mL) and trifluoroacetic anhydride (0.158 g; 0.75mmol) sequentially, and the mixture was warmed at 100° C. overnight. Thereaction mixture was cooled, diluted with water and extracted with ethylacetate. The combined extracts were dried over magnesium sulfate andconcentrated in vacuo. The brown oil was purified by preparativethin-layer chromatography (1 mm silica gel; three elutions with 30%ethyl acetate/hexanes). The purified compound was then dissolved indichloromethane (5 mL). Trifluoroacetic acid (2 mL) was added, and thesolution was kept at room temperature for 1 h and then concentratedunder reduced pressure to afford the title compound as a red gum. LC/MS:271 (M+1).

2-(Trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthridine, hydrochlorideStep A:6-Benzyl-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine

A solution of the crude enamine from Intermediate 20, Step A (904 mg,3.6 mmol) in 15 mL of dry dioxane was cooled to approximately 10° C. and4-ethoxy-1,1,1-trifluoro-3-buten-2-one (0.61 mL, 4.3 mmol) was addeddropwise. The light red solution was allowed to warm to room temperatureovernight, ammonium acetate (600 mg) was added, and the mixture waswarmed to reflux. After 2.5 h, the dark red reaction mixture was cooledand concentrated under reduced pressure. The residue was dissolved inether, washed sequentially with water and saturated brine, dried overmagnesium sulfate and concentrated under reduced pressure. The resultantred oil was purified by flash chromatography (silica gel; 10% ethylacetate/hexanes as eluant) to afford the title compound as an orange,waxy solid. LC/MS 293.1 (M+1).

Step B: 2-(Trifluoromethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine,hydrochloride

Treatment of the intermediate from Step A above with 1-chloroethylchloroformate as described for Intermediate 20, Step C afforded thecrude title compound. Trituration with ether provided the title compoundas a pale orange powder. LC/MS 203.1 (M+1).

5-Methoxy-7-(trifluoromethyl)-1,2,3,4-tetrahydro-2,6-naphthridine,hydrochloride Step A: 3,5-Dibromo-6-(trifluoromethylpyridin-2(1H)-one

A mixture of 2-hydroxy-6-(trifluoromethyl)pyridine (5.00 g, 30.7 mmol)and N-bromosuccinimide (11.46 g, 64.4 mmol) in N,N-dimethylformamide (20mL) was stirred at room temperature overnight. The reaction mixture wasdiluted with ethyl acetate, washed sequentially with water (twice) andsaturated brine, dried over sodium sulfate and concentrated underreduced pressure. The residue was purified by flash columnchromatography (silica gel; 30% ethyl acetate/hexanes as eluant) toyield the title compound. ¹H-NMR (400 MHz, CDCl₃) δ 8.15 (s, 1H).ESI-MS: 322 (M+H+2).

Step B: 3,5-Dibromo-2-methoxy-6-(trifluoromethyl)pyridine

To a suspension of the compound from Step A above (10.0 g, 31.2 mmol)and silver carbonate (5.73 g, 20.8 mmol) in benzene (40 mL) was addediodomethane (2.33 mL, 37.4 mL). The reaction mixture was stirred at 50°C. under nitrogen in the dark for 24 h. The reaction mixture was dilutedwith benzene and filtered. The filtrate was washed sequentially with 5%aqueous sodium bicarbonate solution and water (twice), dried over sodiumsulfate and concentrated. The residue was purified by flash silica gelcolumn chromatography. ¹H NMR (400 MHz, CDCl₃) δ 8.07 (s, 1H), 4.02 (s,3H).

Step C: 3,5-Dibromo-2-methoxy-6-(trifluoromethyl)isonicotinaldehyde

To a flame-dried 100 mL round-bottomed flask, was added dry THF (15 mL).The solution was cooled to −78° C. and then N,N-diisopropylamine (0.46mL, 3.28 mmol), 2.5M n-butyllithium in hexane (1.31 mL, 3.28 mmol), anda solution of the compound from Step B above (1.00 g, 2.99 mmol) in dryTHF (10 mL) were added sequentially. The reaction mixture was stirred at−78° C. for 10 min before methyl formate (0.276 mL, 4.49 mmol) wasslowly added. After the reaction was stirred for another 2 h, themixture was warmed and stirred for 30 min at room temperature. Then themixture was quenched by the addition of saturated aqueous ammoniumchloride solution and extracted with ethyl acetate. The combined organicphases were washed sequentially with water and saturated brine, driedover sodium sulfate and concentrated. The residue was purified by flashchromatography (silica gel; 15% ethyl acetate/hexanes as eluant) toyield the title compound. ¹H NMR (400 MHz, CDCl₃) δ 10.10 (s, 1H), 4.11(s, 3H).

Step D: [3,5-Dibromo-2-methoxy-6-(trifluoromethyl)pyridin-4-yl]methanol

To a solution of3,5-dibromo-2-methoxy-6-(trifluoromethyl)isonicotinaldehyde (980 mg, 2.7mmol) in ethanol (10 mL) was added sodium borohydride (102 mg, 2.7mmol). The reaction mixture was stirred for 20 min, concentrated, andthe residue was purified by flash chromatography (silica gel; 50% ethylacetate/hexanes as eluant) to yield the title compound. ¹H NMR (400 MHz,CDCl₃) δ 5.10 (s, 2H), 4.05 (s, 3H), 2.32 (br s, 1H).

Step E:4-[[[tert-Butyl(dimethyl)silyl]oxy]methyl]-3,5-dibromo-2-methoxy-6-(trifluoromethyl)pyridine

To a solution of the compound from Step D above (880 mg, 2.41 mmol) intetrahydrofuran (3 mL) was added sodium hydride (60 weight % dispersionin oil; 107 mg, 2.65 mmol). After 30 min at room temperature, a solutionof tert-butyl(dimethyl)silyl chloride (434 mg, 2.89 mmol) was added andthe reaction was then stirred for an additional 1 h. The solvent wasevaporated and residue was purified by flash chromatography (silica gel;20% ethyl acetate/hexanes as eluant) to yield the title compound. ¹H NMR(400 MHz, CDCl₃) δ 5.03 (s, 2H), 4.05 (s, 3H), 0.95 (s, 9H), 0.19 (s,6H). LC/MS: 480 (M+H+2).

Step F:3-Bromo-4-[[[tert-butyl(dimethyl)silyl]oxy]methyl]-2-methoxy-6-(trifluoromethyl)pyridine

To a solution of the compound from Step E above (2.68 g, 3.41 mmol) intetrahydrofuran (50 mL) at −78° C. was added 2.0M phenyllithium incyclohexane (1.70 mL, 3.41 mmol). After the reaction was stirred for 5min, 10% citric acid in THF was added. The mixture was diluted withethyl ether, washed sequentially with water and saturated brine, driedover sodium sulfate and concentrated. The residue was purified by flashchromatography (silica gel; 10 to 15% ethyl acetate/hexanes gradientelution) to yield the title compound. ¹H NMR (400 MHz, CDCl₃) δ 7.52 (s,1H), 4.74 (s, 2H), 4.08 (s, 3H), 0.99 (s, 9H), 0.17 (s, 6H). LC/MS:400/402 (M+H and M+H+2).

Step G:3-Allyl-4-[[[tert-butyl(dimethyl)silyl]oxy]methyl-2-methoxy-6-(trifluoromethyl)pyridine

A mixture of3-bromo-4-[[[tert-butyl(dimethyl)silyl]oxy]methyl]-2-methoxy-6-(trifluoromethyl)pyridine(2.51 g, 6.27 mmol), allytributyltin (2.92 mL, 9.41 mmol),tetrakis(triphenylphosphine)palladium(0) (750 mg, 0.627 mmol) andtoluene (15 mL) was flushed with nitrogen several times. The reactionmixture was stirred at reflux overnight. The reaction was filtered andconcentrated under vacuum. The residue was purified by flashchromatography (silica gel; 0 to 5% ethyl acetate/hexanes gradientelution) to yield the title compound. ¹H NMR (400 MHz, CDCl₃) δ 7.55 (s,1H), 5.85 (m, 1H), 4.93-5.11 (m, 2H), 4.74 (s, 2H), 4.04 (s, 3H), 3.37(d, J=5 Hz, 2H), 0.99 (s, 9H), 0.17 (s, 6H).

Step H:[4-[[[tert-Butyl(dimethyl)silyl]oxy]methyl]-2-methoxy-6-(trifluoromethyl)pyridin-3-yl]acetaldehyde

A mixture of the compound from Step G above (2.62 g, 7.25 mmol),N-methylmorpholine N-oxide (849 mg, 7.25 mmol) and osmium tetroxide (4wt. % in water, 10 mL, 400 mg) in acetone/water (4:1) (100 mL) wasstirred at room temperature overnight. The reaction was quenched byaddition of sodium bisulfite (3.50 g, 36 mmol), the acetone was removedunder reduced pressure, the mixture was diluted with water, and theproduct extracted with dichloromethane. The organic layer was dried oversodium sulfate and concentrated, and the residue was stirred with sodiumperiodate (1.86 g, 8.7 mmol) in methanol/water (1:1) (60 mL) for 30 min.The reaction was filtered and concentrated. The residue was partitionedbetween ethyl acetate and water and the aqueous layer was extracted withadditional ethyl acetate. The combined organic extracts were dried oversodium sulfate and concentrated under reduced pressure, and the residuewas purified by flash chromatography (silica gel; 30% ethylacetate/hexanes as eluant) to yield the title compound. ¹H NMR (400 MHz,CDCl₃) δ 9.68 (t, J=1.5 Hz, 1H), 7.46 (s, 1H), 4.67 (s, 2H), 4.01 (s,3H), 3.76 (d, J=5 Hz, 2H), 0.96 (s, 9H), 0.13 (s, 6H).

Step I:N-Benzhydryl-2-[4-[[[tert-butyl(dimethyl)silyl]oxy]methyl]-2-methoxy-6-(trifluoromethyl)pyridin-3-yl]ethanamine

A mixture of the compound from Step H above (1.55 g, 4.26 mmol),aminodiphenylmethane (1.11 mL, 6.40 mmol), and powdered 4 Å molecularsieves (2.80 g) in dichloromethane (20 mL) was stirred for 30 min. Thensodium triacetoxyborohydride (132 mg, 0.625 mmol) was added. Theresultant mixture was stirred overnight, diluted with dichloromethane,filtered, and the filtrate was washed with saturated aqueous sodiumcarbonate solution. The layers were separated, and the aqueous solutionwas extracted with dichloromethane. The combined organic layers weredried over sodium sulfate and concentrated under reduced pressure, andthe residue was purified by flash chromatography (silica gel;dichloromethane as eluant) to yield the title compound. ¹H NMR (CDCl₃,400 MHz) δ 7.48 (s, 1H), 7.18-7.38 (m, 10H), 4.84 (s, 1H), 4.78 (s, 2H),3.81 (s, 3H), 2.77 (m, 4H), 1.62 (br s, 1H), 0.97 (s, 9H), 0.12 (s, 6H).LC/MS: 531 (M+1).

Step J:2-[4-[[[tert-Butyl(dimethyl)silyl]oxy]methyl]-2-methoxy-6-(trifluoromethyl)pyridin-3-yl]ethanamine

To a solution of the compound from Step I above (1.25 g, 2.36 mmol) inabsolute ethanol (100 mL) was added 10% palladium on carbon (480 mg).The reaction mixture was placed in a Parr apparatus and shaken under 50psi of hydrogen for 4 hours. The solution was filtered through a pad ofCelite and concentrated in vacuo to yield the title compound. LC/MS: 365(M+1).

Step K:N-(tert-Butoxycarbonyl)-2-[4-[[[tert-butyl(dimethyl)silyl]oxy]methyl]-2-methoxy-6-(trifluoromethyl)pyridin-3-yl]ethanamine

A mixture of the compound from Step J above (880 mg, 2.41 mmol) anddi-tert-butyl dicarbonate (630 mg, 2.90 mmol) in dichloromethane (20 mL)was stirred at room temperature for 4 h. The mixture was diluted withadditional dichloromethane, washed sequentially with water and saturatedbrine, dried over sodium sulfate and concentrated. The residue waspurified by flash chromatography (silica gel; 20% ethyl acetate/hexanesas eluant) to yield the title compound. ¹H NMR (400 MHz, CDCl₃) δ 7.48(s, 1H), 4.78 (s, 2H), 4.00 (s, 3H), 3.33 (m, 2H), 2.79 (t, 2H, J=7 Hz).

Step L:N-(tert-Butoxycarbonyl)-2-[4-(hydroxymethyl)-2-methoxy-6-(trifluoromethyl)pyridin-3-yl]ethanamine

To a solution of the compound from Step K above (1.12 g, 2.41 mmol) intetrahydrofuran (20 mL) was added tetrabutylammonium fluoride (11.0M intetrahydrofuran, 2.41 mL, 2.41 mmol). The reaction was then stirred atroom temperature for 10 min and concentrated under reduced pressure. Theresidue was purified by flash chromatography (silica gel; 20% to 40%ethyl acetate/hexanes gradient elution) to afford the title compound. ¹HNMR (400 MHz, CDCl₃) δ 7.38 (s, 1H), 4.87 (br s, 1H), 4.76 (d, 2H, J=6Hz), 4.02 (s, 3H), 3.54 (t, 1H), 3.35 (m, 2H), 2.88 (t, 2H, J=6 Hz),1.38 (s, 9H).

Step M:5-Methoxy-7-(trifluoromethyl)-1,2,3,4-tetrahydro-2,6-naphthyridine,hydrochloride

To a solution of the compound from Step L above (342 mg, 0.976 mmol) andtriethylamine (0.82 mL, 5.86 mmol) in dimethyl sulfoxide (3.0 mL) wasadded a solution of sulfur trioxide-pyridine complex (622 mg, 3.905mmol) in dimethyl sulfoxide (10 mL). The reaction was then stirred for40 min, diluted with ethyl acetate, washed sequentially with water andsaturated brine, dried over sodium sulfate and concentrated underreduced pressure. The residue (322 mg, 0.924 mmol) was treated with 4Nhydrogen chloride in 1,4-dioxane (2 mL, 8.0 mmol), and the mixture wasstirred for 4 h. Saturated aqueous sodium bicarbonate solution was addedportionwise to adjust the pH of the mixture to 8, and the product wasextracted with three portions of dichloromethane. The combined organicextracts were dried over sodium sulfate and concentrated under reducedpressure to afford an oil, which was dissolved in dichloromethane (15mL). Sodium triacetoxyborohydride (783 mg, 3.7 mmol) was added, and thereaction mixture was stirred overnight at room temperature. Additionaldichloromethane (15 mL) was added, followed by saturated aqueous sodiumbicarbonate solution (30 mL) and di-tert-butyl dicarbonate (360 mg,1.657 mmol). The resultant biphasic mixture was stirred for 4 h, and thelayers were separated. The aqueous layer was extracted with additionaldichloromethane, and the combined organic extracts were washedsequentially with water and saturated brine, dried over sodium sulfateand concentrated under reduced pressure. The residue was purified byflash chromatography (silica gel; 15% ethyl acetate/hexanes as eluant)to afford the BOC-protected amine (191 mg, 41%), which was treated with4N hydrogen chloride (5 mL) in 1,4-dioxane at room temperature for 18 h.The volatiles were removed under reduced pressure to afford the titlecompound as a pale yellow solid. LC/MS 233.1 (M+1).

2-(Trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine, hydrochlorideStep A:2-(Trifluoromethyl)-7-(triphenylmethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine

A mixture of N-trityl-3-piperidone (1.22 g, 3.6 mmol), magnesium sulfate(2.70 g) and pyrrolidine (0.36 mL, 4.3 mmol) in 10 mL of tetrahydrofuranwas stirred at room temperature for 72 h. The reaction mixture wasfiltered, and the filtrate was concentrated under reduced pressure. Theresultant crude enamine was dissolved in 13 mL of dry dioxane, cooled toapproximately 10° C. and treated dropwise with4-ethoxy-1,1,1-trifluoro-3-buten-2-one (0.61 mL, 4.3 mmol). Theresultant orange solution was allowed to warm to room temperatureovernight. Ammonium acetate (0.60 g) was added to the blood-redsolution, and the mixture was heated at reflux for 2.5 h, cooled to roomtemperature and concentrated under reduced pressure. The residue wasstirred with 100 mL of dry ether, filtered through a pad of Celite, andconcentrated under reduced pressure. The resultant dark red gum waspurified by flash chromatography (silica gel; 3% ethyl acetate/hexanesas eluant) to afford impure product. A portion (147 mg) of this materialwas further purified by preparative TLC (silica gel; 5% ethylacetate/hexanes as eluant) to afford the title compound as a lightyellow foam. LC/MS 365.2 (M+1).

Step B: 2-(Trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine,hydrochloride

A solution of the product (94 mg, 0.20 mmol) from Step A above in 0.5 mLof methanol and 2.0 mL of 4.0M hydrogen chloride in 1,4-dioxane was keptat room temperature for 18 h. The reaction mixture was concentratedunder a stream of nitrogen, and the residue was triturated with ether.The resultant precipitate was collected and dried in vacuo to afford thetitle compound as a pale yellow powder. LC/MS 203.1 (M+1).

Ethyl2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylate,hydrochloride Step A: Ethyl2-(Trifluoromethyl)-7-(triphenylmethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylate

A mixture of N-trityl-3-piperidone (1.22 g, 3.6 mmol), magnesium sulfate(2.70 g) and pyrrolidine (0.36 mL, 4.3 mmol) in 10 mL of tetrahydrofuranwas stirred at room temperature for 72 h. The reaction mixture wasfiltered, and the filtrate was concentrated under reduced pressure. Theresultant crude enamine was dissolved in 15 mL of dry dioxane, cooled toapproximately 10° C. and treated dropwise with ethyl2-(ethoxymethylene)-4,4,4-trifluoro-3-oxobutyrate (0.77 mL, 3.9 mmol).The resultant red-orange solution was allowed to warm to roomtemperature overnight. Ammonium acetate (0.61 g) was added to theblood-red solution, and the mixture was heated at reflux for 3 h, cooledto room temperature and concentrated under reduced pressure. The residuewas stirred with 100 mL of dry ether, filtered through a pad of Celite,and concentrated under reduced pressure. The resultant dark red gum waspurified by flash chromatography (silica gel; 5% ethyl acetate/hexanesas eluant) to afford the title compound as a light orange foam.

Step B: Ethyl2-(Trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylatehydrochloride

A solution of the product (145 mg) from Step A in 0.5 mL of methanol and2.5 mL of 4.0M hydrogen chloride in dioxane was kept at room temperaturefor 3 h. The reaction mixture was concentrated under a stream ofnitrogen, and the residue was triturated with ether. The resultantprecipitate was collected and dried in vacuo to afford the titlecompound as a light red powder. LC/MS 275.1 (M+1).

5,6,7,8-Tetrahydropyrido[4,3-d]pyridine Step A: tert-Butyl4-oxo-3-(dimethylaminomethylidene)-1-piperidinecarboxylate

A solution of tert-butyl 4-oxo-1-piperidinecarboxylate (8.73 g, 44 mmol)and N,N-dimethylformamide dimethyl acetal (5.8 mL, 44 mmol) in 80 mL ofdry N,N-dimethylformamide was warmed at 80° C. for 18 h. The solutionwas cooled and concentrated under reduced pressure, and the residue waspartitioned between ethyl acetate and water. The mixture was filteredthrough a pad of Celite, and the organic layer was separated, washedwith saturated brine, dried over magnesium sulfate and concentratedunder reduced pressure to afford the title compound as an orange oil.

Step B:6-(tert-Butoxycarbonyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine

Formamidine acetate (472 mg, 4.52 mmol) in 15.0 mL of absolute ethanolwas treated with sodium ethoxide (21 wt % solution in ethanol; 1.7 mL).After 30 min, a solution of the product from Step A above (1.15 g) in 8mL of absolute ethanol was added, and the mixture was warmed at refluxfor 18 h. The dark solution was cooled to room temperature andconcentrated under reduced pressure, and the residue was partitionedbetween ethyl acetate and water. The organic layer was separated, washedwith brine, dried over magnesium sulfate and concentrated to an orangeoil. Purification by flash chromatography (silica gel; 2%methanol/dichloromethane as eluant) afforded the title compound as alight yellow gum.

Step C: 5,6,7,8-Tetrahydropyrido[4,3-d]pyrimidine

A solution of the product from Step B above (730 mg) in 10 mL ofdichloromethane was cooled to 0° C. and treated dropwise with 5 mL oftrifluoroacetic acid. The solution was warmed to room temperature and,after 1 h, concentrated under reduced pressure. The residue wasdissolved in methanol and applied to an ion-exchange column (VarianBond-Elut SCX, 5 g; preconditioned with methanol). The column was washedseveral times with methanol, and the amine product was eluted with 1.0Mammonia-methanol. The fractions containing product were concentratedunder reduced pressure to afford the title compound as an orange oil.LC/MS 136.1 (M+1).

2-(Trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine Step A:6-(tert-Butoxycarbonyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine

Reaction of tert-butyl4-oxo-3-(dimethylaminomethylidene)-1-piperidinecarboxylate (1.78 g) fromIntermediate 28, Step A with trifluoroacetamidine (0.86 g) according tothe procedure described for Intermediate 28, Step B, and purification byflash chromatography (silica gel; 18% ethyl acetate/hexanes as eluant),afforded the title compound as a viscous orange oil.

Step B: 2-(Trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine,trifluoroacetatic acid salt

Reaction of the product from Step A above with trifluoroacetic acid indichloromethane according to the procedure outlined for Intermediate 28,Step C afforded the title compound as a white powder. LC/MS 204.0 (M+1).

2-Methyl-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine, trifluoroacetatesalt Step A:6-(tert-Butoxycarbonyl)-2-methyl-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine

Reaction of tert-butyl4-oxo-3-(dimethylaminomethylidene)-1-piperidinecarboxylate (1.15 g) fromIntermediate 28, Step A with acetamidine acetate (0.54 g) according tothe procedure described for Intermediate 28, Step B, and purification byflash chromatography (silica gel; 2% methanol/dichloromethane as eluant)afforded the title compound as a viscous orange oil.

Step B: 2-Methyl-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine,trifluoroacetate salt

Reaction of the product from Step A above with trifluoroacetic acid indichloromethane according to the procedure outlined for Intermediate 28,Step C afforded the title compound as a light orange powder. LC/MS 150.1(M+1).

4-Hydroxy-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine,acetic acid salt Step A:6-Benzyl-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidin-4-ol

To a solution of ethyl 1-benzyl-4-oxo-3-piperidinecarboxylatehydrochloride (2.68 g, 10.3 mmol) in 25 mL of absolute ethanol was added13 mL of 2.68M sodium ethoxide in ethanol dropwise with stirring andcooling in a water bath. After 10 min, trifluoroacetamide (0.92 g, 8.21mmol) was added dropwise. The reaction stirred at reflux (90° C.) for 16h. The mixture was cooled to ambient temperature, concentrated in vacuo,partitioned between water and ethyl acetate, and extracted with threeportions of ethyl acetate. The organic phase was sequentially washedwith brine, dried over magnesium sulfate, and concentrated in vacuo.Purification by flash chromatography (silica gel, 97:7dichloromethane/methanol) gave the title compound. LC/MS 310 (M+1).

Step B:4-Hydroxy-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine,acetic acid salt

To a solution of6-benzyl-2-(trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidin-4-ol(0.08 g, 0.26 mmol) in 5.0 mL of glacial acetic acid was added 70 mg of5% Pd/C. The reaction was shaken (Parr shaker) at room temperature underhydrogen at 42 psi for 13 h. Removal of the catalyst by filtration,followed by concentration and trituration with diethyl ether gave thetitle compound. LC/MS 220 (M+1).

5-Ethyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazine dihydrochloride Step A:Phenyl 5-ethylpyrido[3,4-b]pyrazine-6(5H)-carboxylate

A solution of phenyl chloroformate (0.200 mL, 250 mg, 1.59 mmol) intetrahydrofuran (3.5 mL) was added over 20 min to a solution of 200 mg(1.53 mmol) of pyrido[3,4-b]pyrazine (prepared according to theprocedure of F. F. Duarte and F. D. Popp, J. Heterocyclic Chem., 31:819-823 (1994)) in tetrahydrofuran (7.5 mL) cooled in a −25° C. bath.After 10 min, ethylmagnesium bromide (1.0M in tetrahydrofuran, 1.54 mL,1.54 mmol) was added over 10 min. The mixture was allowed to warm to 0°C. over 1 h. After an additional 30 min at 0° C., water (20 mL) wasadded and the mixture was extracted with ethyl acetate (50 mL). Theorganic layer was washed with saturated sodium bicarbonate solution (10mL) followed by saturated aqueous brine (10 mL). The aqueous layers wereextracted in succession with ethyl acetate (25 mL) and the organiclayers were dried over sodium sulfate, decanted, and evaporated.Purification by flash chromatography (silica gel, 4-5% ethyl acetate in1:1 hexanes/dichloromethane) gave the title compound as a colorlesssyrup. LC/MS 282 (M+1).

Step B: Phenyl5-ethyl-7,8-dihydropyrido[3,4-b]pyrazine-6(5H)-carboxylate

Catalyst (10% palladium on carbon, 140 mg) was added to a solution ofphenyl 5-ethylpyrido[3,4-b]pyrazine-6(5H)-carboxylate (238 mg, 0.85mmol) in ethyl acetate (6.0 mL), and the resultant mixture was stirredunder hydrogen (1 atm) for 7.5 h. Filtration through Celite® andevaporation of the solvent gave the crude product. Purification by flashchromatography (silica gel, 6-15% ethyl acetate/dichloromethane) gavethe title compound as a colorless oil. LC/MS 284 (M+1).

Step C: tert-Butyl5-ethyl-7,8-dihydropyrido[3,4-b]pyrazine-6(5H)-carboxylate

Potassium tert-butoxide (11.0M in tetrahydrofuran, 0.7 mL, 0.7 mmol) wasadded over 3 min to a solution of phenyl5-ethyl-7,8-dihydropyrido[3,4-b]pyrazine-6(5H)-carboxylate (91 mg, 0.32mmol) in tetrahydrofuran (1.8 mL) cooled in a −20 to −30° C. bath. After30 min, the bath was removed and stirring was continued for 75 min. Themixture was added to saturated aqueous sodium bicarbonate solution (10mL) which was then extracted with two portions of ethyl acetate (35 mLand 15 mL). The organic layers were washed in succession with saturatedaqueous brine (10 mL), dried over sodium sulfate, decanted, andevaporated. Purification by flash column chromatography (silica gel, 15%ethyl acetate/hexanes) gave the title compound as a colorless oil. ¹HNMR (500 MHz, CD₃OD) δ 8.43 (d, 1H, J=2 Hz), 8.40 (d, 1H, J=2 Hz),5.17-5.02 (bm, 1H), 4.40-4.25 (bm, 1H), 3.37-3.20 (bm, 1H), 3.04 (ddd,1H, J=17, 12, 6 Hz), 2.90 (dd, 1H, J=17, 4 Hz), 2.10-2.00 (m, 1H),1.87-1.76 (m, 1H), 1.49 (s, 9H), 1.04 (bt, 3H). LC/MS 208 (M+1-56).

Step D: 5-Ethyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazine dihydrochloride

A solution methanolic hydrogen chloride (approx. 1.6M, 1.5 mL) was addedto tert-butyl 5-ethyl-7,8-dihydropyrido[3,4-b]pyrazine-6(5H)-carboxylate(29 mg, 0.11 mmol) dissolved in 0.25 mL of methanol. After 3.5 h, thesolution was concentrated under a stream of nitrogen. Methanol (twoportions) was added, with evaporation of the solvent after eachaddition, to give the title compound as a hygroscopic foam. ¹H NMR (500MHz, CD₃OD) δ 8.57 (d, 1H, J=3 Hz), 8.54 (d, 1, J=3 Hz), 4.57 (dd, 1H,J=8, 5 Hz), 3.77 (ddd, 1H, J=13, 6, 5 Hz), 3.59 (ddd, 1H, J=10, 6 Hz),3.37 (ddd, 1H, J=18, 10, 7 Hz), 3.35 (dt, 1H, J=18, 5 Hz), 2.51-2.41 (m,1H), 2.06-1.96 (m, 1H), 1.18 (t, 3H, J=8 Hz). LC/MS 164 (M+1).

5-Methyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazine dihydrochloride

The title compound was prepared using essentially the same proceduredescribed for INTERMEDIATE 32, with methylmagnesium bromide used inplace of ethylmagnesium bromide in Step A. ¹H NMR (500 MHz, CD₃OD) δ8.58 (d, 1H, J=3 Hz), 8.55 (d, 1H, J=3 Hz), 4.74 (q, 1H, J=7 Hz), 3.77(dt, 1H, J=13, 6 Hz), 3.62 (ddd, 1H, J=13, 9, 6 Hz), 3.38 (ddd, 1H,J=18, 9, 6 Hz), 3.27 (dt, J=18, 6 Hz), 1.77 (d, 3H, J=7 Hz).

8-Methyl-5,6,7,8-tetrahydropyrido[3,4-c]pyridazine, trifluoroacetic acidsalt Step A: 2-Methylpiperidin-3-ol

To a solution of 5.0 g (45.8 mmol) of 3-hydroxy-2-methylpyridine inmethanol was added 5.5 g of rhodium on alumina powder. The reaction wasstirred under an atmosphere of hydrogen at 50 psi overnight. The mixturewas filtered through a pad of Celite and the filtrate was concentratedto give the title compound as a viscous oil.

Step B: tert-Butyl 3-hydroxy-2-methylpiperidine-1-carboxylate

To a solution of 4.80 g (41.7 mmol) of 2-methylpiperidin-3-ol (Step A)in 200 mL of dichloromethane were added N,N-diisopropylethylamine (7.26mL, 41.7 mmol) and di-tert-butyl dicarbonate (9.10 g, 41.7 mmol). Thereaction was stirred at ambient temperature for 4 h. Then the mixturewas partitioned between dichloromethane and 0.5N aqueous sodiumbicarbonate solution. The aqueous phase was extracted with threeportions of dichloromethane. The combined organic layers were washedwith brine, dried over magnesium sulfate, and concentrated. Purificationby flash chromatography on a Biotage® system (silica gel, eluting with20% ethyl acetate/hexane to 60% ethyl acetate/hexane) gave the titlecompound. LC/MS 160 (M+1-56).

Step C: tert-Butyl 2-methyl-3-oxopiperidine-1-carboxylate

A solution of oxalyl chloride (4.06 mL, 46.5 mmol) in 50 mL ofdichloromethane was cooled to −78° C. and 4.95 mL (69.8 mmol) ofdimethyl sulfoxide was added slowly and the mixture was stirred at −78°C. for 10 min. Then a solution of 5.00 g (23.3 mmol) of tert-butyl3-hydroxy-2-methylpiperidine-1-carboxylate (Step B) in 5 mL ofdichloromethane was added dropwise to above mixture. The mixture wasstirred at −78° C. for 20 min, then 40.5 mL (232 mmol) ofN,N-diisopropylethylamine was added to the mixture. The reaction waswarmed to ambient temperature and continued to stir at ambienttemperature for 1 h. The mixture was partitioned between dichloromethaneand water. The aqueous phase was extracted with three potions ofdichloromethane. The combined organic layers were washed with brine,dried over magnesium sulfate, and concentrated. Purification by flashchromatography on a Biotage®D system (silica gel, eluting with 10% ethylacetate/hexane to 30% ethyl acetate/hexane) gave the title compound.LC/MS 214 (M+1).

Step D: tert-Butyl4-[(2E)-1-hydroxyl-3-phenylprop-2-enyl]-2-methyl-3-oxopiperidine-1-carboxylate

To a solution of 2.14 mL (15.3 mmol) of N,N-diisopropylamine in 50 mL oftetrahydrofuran at −78° C. was added 7.96 mL (15.6 mmol, 2.5M in hexane)of n-butyl lithium and the mixture was stirred at −78° C. for 10 min.The reaction was warmed to 0° C. and stirred at 0° C. for 15 min. Themixture was cooled down to −78° C. again, and a solution 2.50 g (11.7mmol) of tert-butyl 2-methyl-3-oxopiperidine-1-carboxylate (Step C) in 5mL of tetrahydrofuran was added to the mixture slowly. The mixture wasstirred at −78° C. for 1 h. Then 1.77 mL (14.9 mmol) oftrans-cinnamaldehyde in 5 mL of tetrahydrofuran (pre-cooled to −78° C.)was added to the reaction mixture and the reaction was stirred at −78°C. for 5 h. The reaction was quenched with saturated aqueous sodiumbicarbonate solution and extracted with three portions of ether. Thecombined organic layers were washed with brine, dried over magnesiumsulfate, and concentrated. Purification by flash chromatography on aBiotage® system (silica gel, eluting with 10% ethyl acetate/hexane to30% ethyl acetate/hexane) gave the tide compound. LC/MS 368 (M+23).

Step E: tert-Butyl4-(1-hydroxyl-2-oxoethyl)-2-methyl-3-oxopiperidine-1-carboxylate

Ozone gas was bubbled into a solution of 0.450 g (1.30 mmol) oftert-butyl4-[(2E)-1-hydroxyl-3-phenylprop-2-enyl]-2-methyl-3-oxopiperidine-1-carboxylate(Step D) in 10 mL of methanol and 10 mL of dichloromethane at −78° C.until the solution turned blue. The reaction was quenched with dimethylsulfide, warmed to ambient temperature, and stirred for 1 h. The mixturewas concentrated in vacuo and purified by flash chromatography on aBiotage® system (silica gel, eluting with 20% ethyl acetate/hexane to60% ethyl acetate/hexane), affording the title compound.

Step F: tert-Butyl8-methyl-5,8-dihydropyrido[3,4-c]pyridazine-7(6H)-carboxylate

To a solution of 70.0 mg (0.258 mmol) of tert-butyl4-(1-hydroxyl-2-oxoethyl)-2-methyl-3-oxopiperidine-1-carboxylate (StepE) in 12 mL of benzene was added hydrazine. The reaction was heated toreflux for 3.5 h and concentrated to afford the title compound. LC/MS194 (M+1-56).

Step G: 8-Methyl-5,6,7,8-tetrahydropyrido[3,4-c]pyridazine,trifluoroacetate salt

To 70.0 mg (0.258 mmol) of tert-butyl8-methyl-5,8-dihydropyrido[3,4-c]pyridazine-7(6H)-carboxylate (Step F)was added 2 mL of trifluoroacetic acid. The reaction was stirred atambient temperature for 1 h and concentrated to afford the titlecompound. LC/MS: 150 (M+1).

3-Methyl-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine, trifluoroaceticacid salt Step A: tert-Butyl 3,6-dihydropyridine-1(2H)-carboxylate

To a solution of 10 g (117 mmol) of commercially available1,2,3,6-tetrahydropyridine in 240 mL of dichloromethane stirred at 0° C.was added 31.5 g (140 mmol) of di-tert-butyl dicarbonate, and stirringwas continued at 0° C. under nitrogen for several minutes. Then thecooling bath was removed, and the solution was stirred at ambienttemperature for 2.5 h. The solution was concentrated in vacuo, and theresidue was purified by flash chromatography (silica gel, 0-5%methanol/dichloromethane followed by 9:1 hexanes/ethyl acetate) toafford the title compound [For a modified preparation, see Nordmann etal., J. Med. Chem., 28: 1109-1111 (1985)]. ¹H NMR (500 MHz, CDCl₃) δ5.84 (br m, 1H), 5.67 (br apparent s, 1H), 3.90 (apparent s, 2H), 3.50(t, J=5.6 Hz, 2H), 2.15 (br apparent s, 2H), 1.49 (s, 9H). LC/MS: 128(M+1-isobutene).

Step B: tert-Butyl 3,4-dihydroxypiperidine-1-carboxylate

To a stirred solution of 21 g (115 mmol) of tert-butyl3,6-dihydropyridine-1(2H)-carboxylate from Step A in 5 mL oftetrahydrofuran was added 300 mL of water, followed by 18 g (149 mmol)of potassium chlorate. Then a solution of 200 mg of osmium tetroxide in30 mL of water was added slowly in portions. The mixture was stirred at80° C. for 16 h. At this time, additional portions of potassium chlorate(11.2 g, 92 mmol) and osmium tetroxide (138 mg) were added, and stirringwas continued at 80° C. for another 3.5 h. The reaction mixture waspartitioned between diethyl ether and water. The aqueous phase wasextracted with dichloromethane and then concentrated in vacuo. Theresultant residue from the aqueous phase was extracted withtetrahydrofuran. The combined organic fractions were concentrated invacuo, and the residue was purified by flash chromatography (silica gel,0-5% methanol/dichloromethane) to give the title compound. ¹H NMR (500MHz, CDCl₃) δ 5.93 (br s, 2H), 3.92 (m, 1H)-3.83 (m, 1H), 3.63 (m, 2H),3.39 (m, 1H), 3.25 (m, 1H), 1.84 (m, 1H), 1.72 (m, 1H), 1.47 (s, 9H).LC/MS: 240 (M+1).

Step C: tert-Butyl 3,4-dioxopiperidine-1-carboxylate

In a dried flask, a solution of 8.8 mL (9.7 g, 125 mmol) of anhydrousdimethyl sulfoxide in 400 mL of anhydrous dichloromethane was stirredunder nitrogen at −60° C. as 15.9 mL (23.6 g, 113 mmol) oftrifluoroacetic anhydride was added dropwise. The resultant solution wasstirred at −60° C. for 20 min, at which time a solution of 8.5 g (39.1mmol) of tert-butyl 3,4-dihydroxypiperidine-1-carboxylate from Step B in100 mL of anhydrous dichloromethane was added via cannula. The solutionwas stirred at −60° C. for 1.5 h, during which time some precipitationoccurred. Then 36.2 mL (26.3 g, 260 mmol) of triethylamine was added,and stirring was continued at −60° C. for an additional 30 min. Thereaction mixture was concentrated in vacuo, and the residue was purifiedby flash chromatography (silica gel, 0-30% ethyl acetate/hexanes) toyield the title compound, which may exist as a mixture of tautomers. ¹HNMR (500 MHz, CDCl₃) δ 7.8-7.6 (br m, <1H), 5.3 (br apparent s, ≦1H),4.00 (m, 2H), 2.69 (t, J=7.5 Hz, 2H), 1.57 (s, 9H). LC/MS: 214 (M+1).

Step D: tert-Butyl3-methyl-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylate

In analogy to a general literature method (Neunhoeffer and Metz, LiebigsAnn. Chem., 1476-1495 (1983)), a solution of 377 mg (1.88 mmol) ofacetamidrazone hydriodide (ethanimidohydrazide hydriodide), preparedfrom methyl ethanimidothioate hydriodide (Singh et al., Indian J. Chem.,21B: 272-273 (1982)) according to the procedure of Zelenin et al., J.Gen. Chem. USSR, 18: 1410-1415 (1982) in 10 mL of absolute ethanol wastreated with 0.36 mL (268 mg, 2.07 mmol) of N,N-diisopropylethylamine,and the solution was stirred under nitrogen at room temperature for 10min. To this was then added dropwise a solution of 400 mg (1.88 mmol) oftert-butyl 3,4-dioxopiperidine-1-carboxylate from Step C. After beingstirred initially at room temperature, the reaction mixture was heatedat reflux for 4.5 h. At this time, an additional 96 mg (0.48 mmol) ofthe amidrazone salt was added, and stirring at reflux was continued for3 h. The reaction mixture was concentrated in vacuo, and the residue waspurified by flash chromatography (silica gel, 30-70% ethylacetate/hexanes, then 95:5 dichloromethane/methanol) to give the titlecompound. The regiochemistry was assigned in analogy to Example 36, StepA, in which both possible regioisomers were isolated and assigned. ¹H N(500 MHz, CDCl₃) δ 4.93 (s, 2H), 3.82 (m, 2H), 3.02 (m, 2H), 2.85 (s,3H, 1.52 (s, 9H). LC/MS: 195 (M+1-isobutene).

Step E: 3-Methyl-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt

A solution of 58 mg (0.23 mmol) of tert-butyl3-methyl-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylate fromStep D in 2 mL of trifluoroacetic acid and 2 mL of dichloromethane wasstirred at room temperature for 20 min and then concentrated in vacuo.Trituration of the residue with diethyl ether gave the title compound asa trifluoroacetate salt. ¹H NMR (500 MHz, CD₃OD) δ 4.16 (apparent s,2H), 3.96 (m, 2H), 2.28 (s, 3H). (The signal for the methylene group atthe 8-position may be obscured by the water peak at δ 4.88.) LC/MS: 151(+1).

3-(Trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt Step A: tert-Butyl3-(trifluoromethyl)-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylate

This material was obtained by reaction of tert-butyl3,4-dioxopiperidine-1-carboxylate from Intermediate 35, Step C, withtrifluoroacetamidrazone (2,2,2-trifluoroethanimidohydrazide), preparedfrom methyl 2,2,2-trifluoroethanimidoate according to the procedure ofBrown and Wetzel, J. Org. Chem., 30: 3729-3733 (1965), essentially asdescribed for Intermediate 35, Step D, except that completion of thecondensation and ring closure required heating in 2-methoxyethanol atreflux for 2 d. Purification of the evaporation residue by flashchromatography (silica gel, 30% ethyl acetate/hexanes) provided thecrude title compound in addition to a minor amount of the otherregioisomer, tert-butyl3-(trifluoromethyl)-7,8-dihydropyrido[3,4-e][1,2,4]triazine-6(5H)-carboxylate.Further purification of the product was achieved by preparative HPLC(YMC Pro C18 column, gradient elution, 40-70% acetonitrile/watercontaining 0.1% trifluoroacetic acid). To prevent decomposition duringisolation, excess N,N-diisopropylethylamine was added to the pooledproduct fractions to neutralize the trifluoroacetic acid prior toconcentration in vacuo. The residue was partitioned between ethylacetate and 5% aqueous citric acid solution. The organic phase waswashed with brine, dried over sodium sulfate, and concentrated to givethe pure title compound. The regioisomers were assigned on the basis of¹H NMR chemical shift differences reported in several papers foranalogous compounds. (See, for example, Konno et al., Heterocycles, 22:2241-2244 (1984) and Neunhoeffer and Böhnisch, Liebigs Ann. Chem.,153-162 (1976).) ¹H NMR (500 MHz, CDCl₃) δ 5.08 (s, 2H), 3.90 (m, 2H),3.21 (m, 2H), 1.54 (s, 9H). LC/MS: 249 (M+1-isobutene).

Step B:3-(Trifluoromethyl)-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt

Essentially following the procedure used for Example 35, Step E,tert-butyl3-(trifluoromethyl)-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylatewas deprotected with trifluoroacetic acid to give the title compound asa trifluoroacetate salt. LC/MS: 205 (M+1).

3-Cyclopropyl-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt Step A: tert-Butyl3-(cyclopropyl)-5,8-dihydropyrido[4,3-e[]1,2,4]triazine-7(6H)-carboxylate

Following a one-pot procedure for conversion of an amidine via itsamidrazone to a 1,2,4-triazine (Neunhoeffer and Weischedel, Liebigs Ann.Chem., 749: 16-23 (1971)), a solution of 175 mg (1.45 mmol) ofcommercially available cyclopropylcarbamidine hydrochloride in 4 mL ofanhydrous ethanol was treated dropwise with 0.452 mL (46.1 mg, 1.45mmol) of anhydrous hydrazine. After being stirred for about 20 min,0.271 mL (201 mg, 1.56 mmol) of N,N-diisopropylethylamine was added. Theresultant solution was added to a suspension of 300 mg (1.41 mmol) oftert-butyl 3,4-dioxopiperidine-1-carboxylate from Intermediate 35, StepC, in a mixture of 1 mL of ethanol and 5 mL of methanol. The resultantsolution was stirred at room temperature for 2 d and then concentratedin vacuo. The residue was purified by flash chromatography (silica gel,30-50% ethyl acetate/hexanes) followed by preparative TLC (silica gel,2:3 dichloromethane/ethyl acetate) to afford the title compound, whichwas separated from the minor regioisomer, tert-butyl3-cyclopropyl-7,8-dihydropyrido[3,4-e][1,2,4]triazine-6(5H)-carboxylate.Regioisomers were assigned as described for Intermediate 36, Step A. ¹HNMR (500 MHz, CDCl₃) δ 4.92 (s, 2H), 3.81 (m, 2H), 2.98 (m, 2H), 2.47(m, 1H), 1.54 (s, 9H), 1.24-1.19 (m, 4H). LC/MS: 221 (M+1-isobutene).

Step B: 3-Cyclopropyl-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt

Essentially following the procedure used for Example 35, Step E,tert-butyl3-(cyclopropyl)-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylatefrom Step A was deprotected with trifluoroacetic acid to give the titlecompound as a trifluoroacetate salt. LC/MS: 177 (M+1).

3-Phenyl-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine, trifluoroaceticacid salt Step A: tert-Butyl3-phenyl-5,8-dihydropyrido[4,3-e][2,4]triazine-7(6H)-carboxylate

Essentially following the procedure used for Intermediate 35, Step D,tert-butyl 3,4-dioxopiperidine-1-carboxylate from Intermediate 35, StepC, was reacted with benzamidrazone hydriodide(benzenecarboximidohydrazide hydriodide), prepared according to theprocedure of Doyle and Kurzer, Synthesis, 583-584 (1974), to give thetitle compound, which was separated from the other regioisomer,tert-butyl3-phenyl-7,8-dihydropyrido[3,4-e][1,2,4]triazine-6(5H)-carboxylate.Regioisomers were assigned as described for Intermediate 36, Step A. ¹HNMR (500 MHz, CDCl₃) δ 8.56 (m, 21), 7.58 (m, 3H), 5.03 (s, 2H), 3.90(t, J=6 Hz, 2H), 3.15 (t, J=6 Hz, 2H), 1.57 (s, 9H). LC/MS: 257(M+1-isobutene).

Step B: 3-Phenyl-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt

Essentially following the procedure used for Example 35, Step E,tert-butyl3-phenyl-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylate fromStep A was deprotected with trifluoroacetic acid to give the titlecompound as a trifluoroacetate salt. LC/MS: 213 (M+1).

3-(4-Fluorophenyl)-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt Step A: tert-Butyl3-(4-fluorophenyl)-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylateand tert-butyl3-(4-fluorophenyl)-7,8-dihydropyrido[3,4-e][1,2,4]triazine-6(5H)-carboxylate

Essentially following the procedure used for Intermediate 37, Step A,4-fluorobenzamidine hydrochloride (Terpinski et al., Magn. Reson. Chem.,25: 923-927 (1987); general method: Moss et al., J. Am. Chem. Soc., 107:2743-2748 (1985)) was reacted with anhydrous hydrazine and then withtert-butyl 3,4-dioxopiperidine-1-carboxylate from Intermediate 35, StepC. Purification of the residue by preparative TLC (silica gel, 7:3dichloromethane/ethyl acetate) afforded the two title compounds.Regioisomers were assigned as described for Intermediate 36, Step A.

tert-Butyl3-(4-Fluorophenyl)-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylate:¹H NMR (500 MHz, CDCl₃) δ 8.56 (m, 2H), 7.23 (m, 2H), 5.00 (s, 2H), 3.88(m, 2H), 3.11 (m, 2H), 1.55 (s, 9H). LC/MS: 331 (M+1).

tert-Butyl3-(4-fluorophenyl)-7,8-dihydropyrido[3,4-e][1,2,4]triazine-6(5H)-carboxylate:¹H NMR (500 MHz, CDCl₃) δ 8.55 (m, 2H), 7.23 (m, 2H), 4.79 (s, 2H), 3.89(m, 2H), 3.31 (m, 2H), 1.55 (s, 9H). LC/MS: 331 (M+1).

Step B:3-(4-Fluorophenyl)-5,6,7,8-tetrahydropyrido[4,3-e][1,2,4]triazine,trifluoroacetic acid salt

Essentially following the procedure used for Example 35, Step E,tert-butyl3-(4-fluorophenyl)-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylatefrom Step A was deprotected with trifluoroacetic acid to give the titlecompound as a trifluoroacetate salt. LC/MS: 231 (M+1).

3-(4-Fluorophenyl)-5,6,7,8-tetrahydropyrido[3,4-e][1,2,4]triazine,trifluoroacetic acid sat

Essentially following the procedure used for Example 35, Step E,tert-butyl3-(4-fluorophenyl)-5,8-dihydropyrido[4,3-e][1,2,4]triazine-7(6H)-carboxylatefrom Intermediate 39, Step A, was deprotected with trifluoroacetic acid,except that reaction time was limited to 4 min in order to preventdecomposition. LC/MS: 231 (M+1).

Note that, in this case, reaction time should also be kept short forremoval of the N-Boc protecting group from the acylated product formedin the next step.

EXAMPLE 1

[4-[[[[(3S)-2-[(3R)-3-Amino-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoguinolin-3-yl]carbonyl]amino]methyl]phenyl]aceticacid trifluoroacetic acid salt Step A: Methyl[4-[[[[(3S)-2-[(3R)-3-[(tert-butoxycarbonyl)amino]-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoguinolin-3-yl]carbonyl]amino]methyl]phenyl]acetate

A mixture of methyl[4-[[[(3S)-1,2,3,4-tetrahydroisoquinolin-3-ylcarbonyl]amino]methyl]phenyl]acetatetrifluoroacetic acid salt (Intermediate 16, 45 mg, 0.10 mmol),commercially available(3R)-3-[(tert-butoxycarbonyl)amino]4-(2-fluorophenyl)butanoic acid (42mg, 0.14 mmol), 1-(3-(dimethylamino)propyl]-3-ethylcarbodiimidehydrochloride (EDC; 29 mg, 0.15 mmol), 1-hydroxybenzotriazole (HOBt; 20mg, 0.15 mmol) and N,N-diisopropylethylamine (0.052 mL, 0.30 mmol) in1.0 mL of dichloromethane was stirred at room temperature for 2 h. Thereaction mixture was subjected directly to flash chromatography (silicagel; 60% ethyl acetate/hexanes as eluant) to afford the title compoundas a viscous oil.

Step B:[4-[[[[(3S)-2-[(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoguinolin-3-yl]carbonyl]amino]methyl]phenyl]aceticacid, lithium salt

To a stirred solution of the compound from Step A above in 1.8 mL of3:2:1 tetrahydrofuran/methanol/water was added 10 mg of lithiumhydroxide monohydrate. The mixture was stirred at room temperature for1.5 h, and was then concentrated under reduced pressure to afford thetitle compound as a nearly colorless gum.

Step C:[4-[[[[(3S)-2-[(3R)-3-Amino-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoguinolin-3-yl]carbonyl]amino]methyl]phenyl]aceticacid, trifluoroacetic acid salt

The product from Step B above was suspended in 2 mL of dichloromethaneand 1 mL of trifluoroacetic acid was added. After stirring at roomtemperature for 1 h, the solution was concentrated under reducedpressure and purified by preparative HPLC (YMC Pro C18 column, gradientelution, 10-90% acetonitrile/water containing 0.1% trifluoroacetic acid)to afford the title compound as a white powder. LC/MS: 504.2 (M+1).

EXAMPLE 2

N-[2-[(3R)-3-Amino-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoguinolin-7-yl]benzenesulfonamide,trifluoroacetic acid salt Step A:2-[(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2-fluorophenyl)butanoyl]-7-nitro-1,2,3,4-tetrahydroisoquinoline

(3R)-3-[(tert-Butoxycarbonyl)amino]4-(2-fluorophenyl)butanoic acid (0.69g; 2.34 mmol) and 7-nitro-1,2,3,4 tetrahydroisoquinoline (0.50 g; 2.34mmol) were treated with EDC (0.54 g, 2.8 mmol), HOBt (0.38 g, 2.8 mmol)and N,N-diisopropylethylamine (0.60 g, 4.67 mmol) essentially followingthe procedure outlined in Example 1, Step A. Purification by flashchromatography (silica gel; 35% ethyl acetate/hexanes as eluant)afforded the title compound. LC/MS: 358.1 (M+1-BOC)

Step B:7-Amino-2-[(3R)-3-[(tert-butoxycarbonyl)amino]-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoquinoline

To the product (0.43 g) from Step A above in 4 mL of methanol was added20% palladium hydroxide on carbon (Pearlman's catalyst, 0.04 g). Thereaction was placed under a balloon of hydrogen and allowed to stir atroom temperature overnight. The reaction flask was purged, the mixturewas filtered and concentrated in vacuo. The residue was purified byflash chromatography (silica gel; 55% ethyl acetate/hexanes) to affordthe title compound. LC/MS: 328 (M−100).

Step C:N-[2-[(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoguinolin-7-yl]benzenesulfonamide

To an ice-cold solution of the product (0.040 g; 0.09 mmol) from Step Babove in dichloromethane (0.5 mL) was added sequentially pyridine (0.011g, 0.14 mmol) and benzenesulfonyl chloride (0.018 g, 0.103 mmol), andthe reaction was then allowed to warm to room temperature overnight. Thevolatiles were removed under reduced pressure and the residue waspurified by flash chromatography (silica gel; 50% ethyl acetate/hexanesas eluant) to afford the title compound. LC/MS: 568.1 (M+1).

Step D:N-[2-[(3R)-3-Amino-4-(2-fluorophenyl)butanoyl]-1,2,3,4-tetrahydroisoguinolin-7-yl]benzenesulfonamide,trifluoroacetic acid salt

To the product from Step C was added 1 mL of dichloromethane and 2 mL oftrifluoroacetic acid. The reaction was allowed to stand at roomtemperature for 2 h and the volatiles were removed under reducedpressure to afford the title compound. LC/MS: 468.1: (M+1).

EXAMPLE 3

7-[(3R)-3-Amino-4-(2,5-difluorophenyl)butanoyl]-2-(trifluoromethyl)-5-6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylicacid, trifluoroacetic acid salt Step A: Ethyl7-[(3R)-3-[(tert-butoxycarbonyl)amino]-4-(2,5-difluorophenyl)butanoyl]-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylate

(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,5-difluorophenyl)butanoic acid(intermediate 1) and ethyl2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylatehydrochloride (intermediate 27) were treated with EDC, HOBt andN,N-diisopropylethylamine according to the procedure described forExample 1, Step A to afford the title compound as a white foam.

Step B:7-[(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,5-difluorophenyl)butanoyl]-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylicacid

A solution of the product from Step A above (92 mg, 0.161 mmol) in 1.2mL of 3:2:1 tetrahydrofuran/methanol/water was treated with lithiumhydroxide monohydrate (10 mg) and the solution was stirred at roomtemperature for 18 h. The volatiles were removed under a stream ofnitrogen, and the residue was dissolved in 4 mL of water. The solutionwas acidified by portionwise addition of citric acid monohydrate, andthe product was extracted into ethyl acetate. The combined organicextracts were dried over magnesium sulfate and concentrated to affordthe title compound as a white foam.

Step C:7-[(3R)-3-Amino-4-(2,5-difluorophenyl)butanoyl]-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxylicacid, trifluoroacetic acid salt

A solution of the product from Step B above (23 mg) in 3 mL ofdichloromethane was treated with 1 mL of trifluoroacetic acid, and thesolution was kept at room temperature for 1 h. The volatiles wereremoved under a stream of nitrogen, and the residue was triturated withether. The product was collected and dried in vacuo to afford the titlecompound as a white powder. LC/MS: 444.0 (M+1).

EXAMPLE 4

7-[(3R)-3-Amino-4-(2,5-difluorophenyl)butanoyl]-N-(tert-butyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxamide,hydrochloride Step A:7-[(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,5-difluorophenyl)butanoyl]-N-(tert-butyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxamide

To a solution of the product (33 mg, 0.061 mmol) from Example 3, Step B,1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (EDC; 12mg, 0.063 mmol), 1-hydroxybenzotriazole (HOBt; 9 mg, 0.067 mmol) andN,N-diisopropylethyl amine (0.026 mL, 0.15 mmol) in 1.0 mL ofdichloromethane was added tert-butylamine (0.011 mL, 0.100 mmol). Thesolution was stirred at room temperature for 18 h. The reaction mixturewas subjected directly to flash chromatography (silica gel; 35 to 75%ethyl acetate/hexanes step-gradient elution) to afford the titlecompound as a white foam.

Step B:7-[(3R)-3-Amino-4-(2,5-difluorophenyl)butanoyl]-N-(tert-butyl)-2-(trifluoromethyl)-5,6,7,8-tetrahydro-1,7-naphthyridine-3-carboxamide,hydrochloride

A solution of the product (25 mg) from Step A above, 0.5 mL of methanoland 2.5 mL of 4.0M hydrogen chloride in 1,4-dioxane was kept at roomtemperature for 18 h. The volatiles were removed under a stream ofnitrogen, and the residue was triturated with ether. The resultantprecipitate was collected and dried in vacuo to afford the titlecompound as a white powder. LC/MS: 499.1 (M+1).

EXAMPLE 5

7-[(3R)-3-Amino-4-(2,4,5-trifluorophenyl)butanoyl]-8-methyl-5,6,7,8-tetrahydropyrido[3,4-c]pyridazine,trifluoroacetic acid salt Step A:7-[(3R)-3-[(tert-Butoxycarbonyl)amino]-4-(2,4,5-trifluorophenyl)butanoyl]-8-methyl-5,6,7,8-tetrahydropyrido[3,4-c]pyridazine

To a solution of 73.9 mg (0.281 mmol) of8-methyl-5,6,7,8-tetrahydropyrido[3,4-c]pyridazine, trifluoroacetatesalt (Intermediate 34), 93.6 mg (0.281 mmol) of(3R)-3-[(tert-butoxycarbonyl)amino]4-(2,4,5-trifluorophenyl)butanoicacid (Intermediate 3) and 0.150 mL (0.843 mmol) ofN,N-diisopropylethylamine in 2.5 ml of DMF were addedO-(7-azabenzotriazol-yl)-N,N,N′,N′-tetra-methyluroniumhexafluorophosphate (HATU; 128 mg, 0.337 mmol),1-hydroxy-7-azabenzotriazole (HOAt; 45.9 mg, 0.337 mmol). The reactionwas stirred at room temperature for 18 h. Then the reaction mixture waspartitioned between ethyl acetate and 0.5M aqueous sodium bicarbonatesolution. The aqueous phase was extracted with three portions of ethylacetate. The combined organic phase was washed with brine, dried overmagnesium sulfate and concentrated in vacuo. The mixture was purified bypreparative TLC (100% ethyl acetate), then by chiral HPLC (ChiralCell OJcolumn, 14% ethanol/hexanes) to afford the title compound as a solid.The slower eluting isomer was used in Step B below. LC/MS: 409 (M+1-56).

Step B:7-[(3R)-3-Amino-4-(2,4,5-trifluorophenyl)butanoyl]-8-methyl-5,6,7,8tetrahydropyrido[3,4-c]pyridazine, trifluoroacetic acid salt

The title compound was prepared from7-[(3R)-3-[(tert-butoxycarbonyl)amino]-4-(2,4,5-trifluorophenyl)butanoyl]-8-methyl-5,6,7,8-tetrahydropyrido[3,4-c]pyridazine(Step A) using a procedure analogous to that of Example 1, Step C togive the title compound as a solid. LC/MS: 365 (M+1).

EXAMPLE 6

6-[(3R)-3-Amino-4-(2,4,5-trifluorophenyl)butanoyl]-5-ethyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazineStep A:6-[(3R)-3-(tert-Butoxycarbonylamino)-4-(2,4,5-trifluorophenyl)butanoyl]-5-ethyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazine

5-Ethyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazine dihydrochloride(Intermediate 32, 26 mg, 0.11 mmol) was dissolved inN,N-dimethylformamide (DMF, 0.75 mL) containingN,N-diisopropylethylamine (0.046 mL, 34 mg, 0.26 mmol).(3R)-3-(tert-Butoxycarbonylamino)4 (2,4,5-trifluorophenyl)butanoic acid(Intermediate 3, 36 mg, 0.11 mmol), 1-hydroxybenzotriazole (16 mg, 0.12mmol), and a portion of molecular sieve pellets (4 Å) were added,followed 10 min later by 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimidehydrochloride (33 mg, 0.17 mmol). After stirring for 16 h at roomtemperature, the mixture was partitioned between ethyl acetate (25 mL)and saturated aqueous sodium bicarbonate solution (10 mL). The organiclayer was washed with saturated aqueous brine (10 mL) and the aqueouslayers were extracted in succession with ethyl acetate (25 mL). Theorganic layers were dried over sodium sulfate, decanted, and evaporated.Purification by flash column chromatography (silica gel, 15-20% ethylaceate/0.75-1.0% methanol/dichloromethane) gave the title compound as amixture of diastereomers. Separation was accomplished by EPLC using aChiralcel OJ column, eluting with 8% ethanol in hexanes. Thefirst-eluting diastereomer was used in Step B to produce the more activefinal product. LC/MS: 501 (M+Na).

Step B:6-[(3R)-3-Amino-4-(2,4,5-trifluorophenyl)butanoyl]-5-ethyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazine

A solution of methanolic hydrogen chloride (approx. 1.6M, 1.5 mL) wasadded to6-[(3R)-3-(tert-butoxycarbonylamino)-4-(2,4,5-trifluorophenyl)butanoyl]-5-ethyl-5,6,7,8-tetrahydropyrido[3,4-b]pyrazine(18 mg, 0.038 mmol) dissolved in 0.25 mL of methanol. After 2.5 h, thesolution was added to saturated aqueous sodium bicarbonate solution (10mL), which was then extracted with two portions of ethyl acetate (25 mLand 15 mL). The organic layers were washed in succession with saturatedaqueous brine (5 mL), dried over sodium sulfate, decanted, andconcentrated. The residue was dissolved in methanol, and the resultingsolution was filtered (0.45 micron PTFE membrane) and evaporated toprovide the title compound as a very viscous colorless syrup. LC/MS: 379(M+1).

Essentially following the procedures outlined for Examples 1-6, thecompounds listed in Tables 2 and 3 were prepared.

TABLE 2

Example R² R⁹ MS (M + 1) 7 2-F,5-F pyrrolidin-1-ylcarbonyl 428.2 8 2-Fpiperidin-1-ylcarbonyl 424.0 9 2-F 4-[(methoxycarbonyl)methyl] 518.3benzylaminocarbonyl 10 2-F 4-[(benzyloxy)carbonyl]piperazin-1- 559.0ylcarbonyl 11 2-F,5-F 4-[(benzyloxy)carbonyl]piperazin-1- 577.3ylcarbonyl

TABLE 3

MS Ex. R² R⁸ W X Y Z (M + 1) 12 2-F,5-F H C—H C—H C—H C—H 331.2 132-F,5-F H C—H C—OMe C—OMe C—H 391.2 14 2-F,5-F H C—H C—H C—CN C—H 356.215 2-F,5-F H C—H C—CO₂Me C—H C—H 389.2 16 2-F,5-F H C—H C—CO₂H C—H C—H375.2 17 2-F H C—H C—NHAc C—H C—H 370.1 18 2-F H C—H C—NHSO₂Me C—H C—H406.2 19 3-F,4-F H C—H C—NHSO₂Me C—H C—H 424.2 20 3-F,4-F H C—HC—NHSO₂Ph C—H C—H 486.2 21 2-F,5-F H C—H C—CF₃ C—H C—H 399.0 22 2-F,5-FH C—H C—H C—OH C—H 347.2 23 2-F,5-F H C—H C—H C—H C—OH 347.2 24 2-F,5-FH C—H C—SO₂NH₂ C—H C—H 410.1 25 2-F,5-F H C—H N C—H N 333.1 26 2-F,5-F HC—H N C-Me N 347.1 27 2-F,5-F H C—H N C—CF₃ N 401.1 28 2-F,5-F H C—OH NC—CF₃ N 417.1 29 2-F,5-F H C—H C—CO₂Et C—CF₃ N 472.1 30 2-F,5-F H C—HC—CO₂H C—CF₃ N 444.1 31 2-F,5-F H C—H C—CO₂Me C—CF₃ N 458.2 32 2-F,5-F HC—H C—CO₂Et C—H N 404 33 2-F,5-F H C—H C—CO₂H C—H N 376.2 34 3-F,4-F HC—H C—CO₂H C—Cl N 410 35 2-F,5-F H C—H C—CO₂Et C—Cl N 438.2 36 2-F,5-F HC—H C—CO₂H C—Cl N 410.1 37 2-F,5-F H C—H C—CO₂Et C—OH N 420.0 38 2-F,5-FH C—H C—CO₂H C—OH N 392.1 39 2-F,5-F H C—H C—H C—CF₃ N 400.1 40 2-F,5-FH C—H C—CF₃ C—H N 400.0 41 2-F,5-F H C—H C-[5-(trifluoro-methyl) C—H N468.1 oxadiazol-3-yl] 42 2-F,5-F H N C—CF₃ C—H C—H 400.0 43 2-F,4-F,5-FH C—H C—CF₃ N OMe 448.0 44 2-F,4-F,5-F H N N C-Ph N 428 45 2-F,4-F,5-F HN N C-Me N 366 46 2-F,4-F,5-F H N N C-(4-F-Ph) N 446 47 2-F,4-F,5-F H NN C-cyclopropyl N 392 48 2-F,4-F,5-F H N N C—CF₃ N 420 49 2-F,4-F,5-F HN C-(4-F-Ph) N N 446 50 2-F,4-F,5-F Me N C—H C—H N 365

EXAMPLE OF A PHARMACEUTICAL FORMULATION

As a specific embodiment of an oral pharmaceutical composition, a 100 mgpotency tablet is composed of 100 mg of any of the compounds of thepresent invention, 268 mg microcrystalline cellulose, 20 mg ofcroscarmellose sodium, and 4 mg of magnesium stearate. The active,microcrystalline cellulose, and croscarmellose are blended first. Themixture is then lubricated by magnesium stearate and pressed intotablets.

While the invention has been described and illustrated with reference tocertain particular embodiments thereof, those skilled in the art willappreciate that various adaptations, changes, modifications,substitutions, deletions, or additions of procedures and protocols maybe made without departing from the spirit and scope of the invention.For example, effective dosages other than the particular dosages as setforth herein above may be applicable as a consequence of variations inresponsiveness of the mammal being treated for any of the indicationswith the compounds of the invention indicated above. The specificpharmacological responses observed may vary according to and dependingupon the particular active compounds selected or whether there arepresent pharmaceutical carriers, as well as the type of formulation andmode of administration employed, and such expected variations ordifferences in the results are contemplated in accordance with theobjects and practices of the present invention. It is intended,therefore, that the invention be defined by the scope of the claimswhich follow and that such claims be interpreted as broadly as isreasonable.

1. A compound of structural formula I:

or a pharmaceutically acceptable salt thereof; wherein each n isindependently 0, 1, or 2; W, X, Y, and Z are each independently N orCR^(1;) with the proviso that at least one and only of W, X, Y and Z isN; Ar is phenyl substituted with one to five R² substituents; each R¹ isindependently selected from the group consisting of hydrogen, halogen,hydroxy, cyano, C₁₋₁₀ alkyl, wherein alkyl is unsubstituted orsubstituted with one to five substituents independently selected fromhalogen or hydroxy, C₁₋₁₀ alkoxy, wherein alkoxy is unsubstituted orsubstituted with one to five substituents independently selected fromhalogen or hydroxy, C₁₋₁₀ alkylthio, wherein alkylthio is unsubstitutedor substituted with one to five substituents independently selected fromhalogen or hydroxy, C₂₋₁₀ alkenyl, wherein alkenyl is unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, COOH, and COOC₁₋₆ alkyl, (CH₂)_(n)COOH,(CH₂)_(n)COOC₁₋₆ alkyl, (CH₂)_(n)CONR³R⁴, wherein R³ and R⁴ areindependently selected from the group consisting of hydrogen,tetrazolyl, thiazolyl, (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆ cycloalkyl, andC₁₋₆ alkyl, wherein alkyl is unsubstituted or substituted with one tofive halogens and wherein phenyl and cycloalkyl are unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, C₁₋₆ alkyl, C₁₋₆ alkoxy, (CH₂)_(n)COOH, and(CH₂)_(n)COOC₁₋₆ alkyl, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens; or R³ and R⁴ together with thenitrogen atom to which they are attached form a heterocyclic ringselected from azetidine, pyrrolidine, piperidine, piperazine, andmorpholine wherein said heterocyclic ring is unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, (CH₂)_(n)COOH, (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆ alkyl, andC₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted or substitutedwith phenyl or one to five halogens; (CH₂)_(n)—NR³R⁴,(CH₂)_(n)—OCONR³R⁴, (CH₂)_(n)—SO₂NR³R⁴, (CH₂)_(n)—SO₂R⁵,(CH₂)_(n)—NR⁶SO₂R⁵, (CH₂)_(n)—NR⁶CONR³R⁴, (CH₂)_(n)—NR⁶COR⁶,(CH₂)_(n)—NR⁶CO₂R⁵, (CH₂)_(n)—COR⁶, (CH₂)_(n)—C₃₋₆ cycloalkyl, whereincycloalkyl is unsubstituted or substituted with one to threesubstituents independently selected from halogen, hydroxy, C₁₋₆ alkyl,and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens, (CH₂)_(n)-aryl, wherein aryl isunsubstituted or substituted with one to five substituents independentlyselected from halogen, cyano, hydroxy, NR⁶SO₂R⁵, SO₂R⁵, CO₂H, COOC₁₋₆alkyl, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy areunsubstituted or substituted with one to five halogens,(CH₂)_(n)-heteroaryl, wherein heteroaryl is unsubstituted or substitutedwith one to three substituents independently selected from hydroxy,halogen, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy areunsubstituted or substituted with one to five halogens, and(CH₂)_(n)-heterocyclyl, wherein heterocyclyl is unsubstituted orsubstituted with one to three substituents independently selected fromoxo, hydroxy, halogen, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl andalkoxy are unsubstituted or substituted with one to five halogens,wherein any methylene (CH₂) carbon atom in R¹ is unsubstituted orsubstituted with one to two groups independently selected from halogen,hydroxy, and C₁₋₄ alkyl unsubstituted or substituted with one to fivehalogens; each R² is independently selected from the group consisting ofhydrogen, halogen, cyano, hydroxy, C₁₋₆ alkyl, unsubstituted orsubstituted with one to five halogens, and C₁₋₆ alkoxy, unsubstituted orsubstituted with one to five halogens; each R⁵ is independently selectedfrom the group consisting of tetrazolyl, thiazolyl, (CH₂)_(n)-phenyl,(CH₂)_(n)—C₃₋₆ cycloalkyl, and C₁₋₆ alkyl, wherein alkyl isunsubstituted or substituted with one to five halogens and whereinphenyl and cycloalkyl are unsubstituted or substituted with one to fivesubstituents independently selected from halogen, hydroxy, C₁₋₆ alkyl,and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens, and wherein any methylene (CH₂)carbon atom in R⁵ is unsubstituted or substituted with one to two groupsindependently selected from halogen, hydroxy, C₁₋₄ alkyl, and C₁₋₄alkoxy, wherein alkyl and alkoxy are unsubstituted or substituted withone to five halogens; each R⁶ is hydrogen or R⁵; R⁷, R⁸, and R⁹ are eachindependently selected from the group consisting of hydrogen, cyano,(CH₂)_(n)COOH, (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₁₀ alkyl, unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, C₁₋₆ alkoxy, and phenyl-C₁₋₃ alkoxy, wherein alkoxy isunsubstituted or substituted with one to five halogens, (CH₂)_(n)-aryl,wherein aryl is unsubstituted or substituted with one to fivesubstituents independently selected from halogen, hydroxy, C₁₋₆ alkyl,and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens, (CH₂)_(n)-heteroaryl, whereinheteroaryl is unsubstituted or substituted with one to threesubstituents independently selected from hydroxy, halogen, C₁₋₆ alkyl,and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens, (CH₂)_(n)-heterocyclyl, whereinheterocyclyl is unsubstituted or substituted with one to threesubstituents independently selected from oxo, hydroxy, halogen, C₁₋₆alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens, (CH₂)_(n)—C₃₋₆ cycloalkyl,wherein cycloalkyl is unsubstituted or substituted with one to threesubstituents independently selected from halogen, hydroxy, C₁₋₆ alkyl,and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens, and (CH₂)_(n)CONR³R⁴, wherein R³and R⁴ are independently selected from the group consisting of hydrogen,tetrazolyl, thiazolyl, (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆ cycloalkyl, andC₁₋₆ alkyl, wherein alkyl is unsubstituted or substituted with one tofive halogens and wherein phenyl and cycloalkyl are unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, C₁₋₆ alkyl, C₁₋₆ alkoxy, (CH₂)_(n)COOH, and(CH₂)_(n)COOC₁₋₆ alkyl, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens; or R³ and R⁴ together with thenitrogen atom to which they are attached form a heterocyclic ringselected from azetidine, pyrrolidine, piperidine, piperazine, andmorpholine wherein said heterocyclic ring is unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, (CH₂)_(n)COOH, (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆ alkyl, andC₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted or substitutedwith phenyl or one to five halogens; and wherein any methylene (CH₂)carbon atom in R⁷, R⁸ or R⁹ is unsubstituted or substituted with one totwo groups independently selected from halogen, hydroxy, and C₁₋₄ alkylunsubstituted or substituted with one to five halogens.
 2. The compoundof claim 1 of structural formula Ia wherein the carbon atom marked withan * has the R configuration


3. The compound of claim 1 of structural formula Ie:


4. The compound of claim 3 of structural formula If wherein the carbonatom marked with an * has the R configuration:


5. The compound of claim 3 wherein R⁸ and R⁹ are hydrogen.
 6. Thecompound of claim 1 of structural formula Ih:


7. The compound of claim 6 of structural formula Ii wherein the carbonatom marked with an * has the R configuration:


8. The compound of claim 6 wherein R⁸ and R⁹ are hydrogen.
 9. Thecompound of claim 1 of structural formula Ik:


10. The compound of claim 9 of structural formula Il wherein the carbonatom marked with an * has the R configuration:


11. The compound of claim 9 wherein R⁸ and R⁹ are hydrogen.
 12. Thecompound of claim 1 wherein R² is selected from the group consisting ofhydrogen, fluoro, chloro, bromo, trifluoromethyl, and methyl.
 13. Thecompound of claim 1 wherein R¹ is selected from the group consisting of:hydrogen, halogen, hydroxy, cyano, C₁₀ alkyl, wherein alkyl isunsubstituted or substituted with one to five substituents independentlyselected from halogen or hydroxy, C₁₋₁₀ alkoxy, wherein alkoxy isunsubstituted or substituted with one to five substituents independentlyselected from halogen or hydroxy, (CH₂)_(n)COOH, (CH₂)_(n)COOC₁₋₆ alkyl,(CH₂)_(n)CONR³R⁴, wherein R³ and R⁴ are independently selected from thegroup consisting of hydrogen, tetrazolyl, thiazolyl, (CH₂)_(n)-phenyl,(CH₂)_(n)—C₃₋₆ cycloalkyl, and C₁₋₆ alkyl, wherein alkyl isunsubstituted or substituted with one to five halogens and whereinphenyl and cycloalkyl are unsubstituted or substituted with one to fivesubstituents independently selected from halogen, hydroxy, C₁₋₆ alkyl,C₁₋₆ alkoxy, (CH₂)_(n)COOH, and (CH₂)_(n)COOC₁₋₆ alkyl, wherein alkyland alkoxy are unsubstituted or substituted with one to five halogens; or R³ and R⁴ together with the nitrogen atom to which they are attachedform a heterocyclic ring selected from azetidine, pyrrolidine,piperidine, piperazine, and morpholine wherein said heterocyclic ring isunsubstituted or substituted with one to five substituents independentlyselected from halogen, hydroxy, (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆ alkyl, andC₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted or substitutedwith phenyl or one to five halogens; (CH₂)_(n)—SO₂NR³R⁴,(CH₂)_(n)—NR⁶SO₂R⁵, (CH₂)_(n)—NR⁶COR⁶, (CH₂)_(n)—C₃₋₆ cycloalkyl,wherein cycloalkyl is unsubstituted or substituted with one to threesubstituents independently selected from halogen, hydroxy, C₁₋₆ alkyl,and C₁₋₆ alkoxy, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens, (CH₂)_(n)-aryl, wherein aryl isunsubstituted or substituted with one to five substituents independentlyselected from halogen, cyano, hydroxy, NR⁶SO₂R⁵, SO₂R⁵, CO₂H, COOC₁₋₆alkyl, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy areunsubstituted or substituted with one to five halogens,(CH₂)_(n)-heteroaryl, wherein heteroaryl is unsubstituted or substitutedwith one to three substituents independently selected from hydroxy,halogen, C₁₋₆ alkyl, and C₁₋₆ alkoxy, wherein alkyl and alkoxy areunsubstituted or substituted with one to five halogens, and wherein anymethylene (CH₂) carbon atom in R¹ is unsubstituted or substituted withone to two groups independently selected from halogen, hydroxy, and C₁₋₄alkyl unsubstituted or substituted with one to five halogens.
 14. Thecompound of claim 13 wherein R¹ is selected from the group consisting ofhydrogen, methyl, trifluoromethyl, phenyl, 4-fluorophenyl, cyclopropyl,chloro, methoxy, hydroxy, cyano, methoxycarbonyl, ethoxycarbonyl,tert-butylaminocarbonyl, carboxy, acetamido, methanesulfonylamino,benzenesulfonylamino, aminosulfonyl, and5-(trifluoromethyl)oxadiazol-3-yl.
 15. The compound of claim 1 whereinR⁷, R⁸, and R⁹ are each independently selected from the group consistingof: hydrogen, C₁₋₁₀ alkyl, unsubstituted or substituted with one to fivesubstituents independently selected from halogen, hydroxy, C₁₋₆ alkoxy,and phenyl-C₁₋₃ alkoxy, wherein alkoxy is unsubstituted or substitutedwith one to five halogens, and (CH₂)_(n)CONR³R⁴, wherein R³ and R⁴ areindependently selected from the group consisting of hydrogen,tetrazolyl, thiazolyl, (CH₂)_(n)-phenyl, (CH₂)_(n)—C₃₋₆ cycloalkyl, andC₁₋₆ alkyl, wherein alkyl is unsubstituted or substituted with one tofive halogens and wherein phenyl and cycloalkyl are unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, C₁₋₆ alkyl, C₁₋₆ alkoxy, (CH₂)_(n)COOH, and(CH₂)_(n)COOC₁₋₆ alkyl, wherein alkyl and alkoxy are unsubstituted orsubstituted with one to five halogens;  or R³ and R⁴ together with thenitrogen atom to which they are attached form a heterocyclic ringselected from azetidine, pyrrolidine, piperidine, piperazine, andmorpholine wherein said heterocyclic ring is unsubstituted orsubstituted with one to five substituents independently selected fromhalogen, hydroxy, (CH₂)_(n)COOC₁₋₆ alkyl, C₁₋₆ alkyl, and C₁₋₆ alkoxy,wherein alkyl and alkoxy are unsubstituted or substituted with phenyl orone to five halogens; and wherein any methylene (CH₂) carbon atom in R⁷,R⁸ or R⁹ is unsubstituted or substituted with one to two groupsindependently selected from halogen, hydroxy, and C₁₋₄ alkylunsubstituted or substituted with one to five halogens.
 16. The compoundof claim 15 wherein R⁷, R⁸, and R⁹ are each independently selected fromthe group consisting of hydrogen, methyl, ethyl,[[4-(carboxymethyl)phenyl]methyl]aminocarbonyl, pyrrolidin-1-ylcarbonyl,piperidin-1-ylcarbonyl, 4-[(methoxycarbonyl)methyl]benzylaminocarbonyl,and 4-[(benzyloxy)carbonyl]piperazin-1-ylcarbonyl.
 17. The compound ofclaim 16 wherein R⁷ and R⁹ are hydrogen.
 18. The compound of claim 16wherein R⁸ and R⁹ are hydrogen.
 19. The compound of claim 18 wherein R⁷is hydrogen.
 20. The compound of claim 16 which is selected from thegroup consisting of:

or a pharmaceutically acceptable salt thereof.
 21. A pharmaceuticalcomposition which comprises a compound of claim 1 and a pharmaceuticallyacceptable carrier.
 22. A method for treating non-insulin dependent(Type 2) diabetes in a mammal in need thereof which comprises theadministration to the mammal of a therapeutically effective amount of acompound of claim
 1. 23. A method for treating hyperglycemia in a mammalin need thereof which comprises the administration to the mammal of atherapeutically effective amount of a compound of claim
 1. 24. Thepharmaceutical composition of claim 21 further comprising one or moreadditional active ingredients selected from the group consisting of: (a)a second dipeptidyl peptidase IV inhibitor; (b) an insulin sensitizerselected from the group consisting of a PPARγ agonist, a PPARα/γ dualagonist, a PPARα agonist, a biguanide, and a protein tyrosinephosphatase-1B inhibitor; (c) an insulin or insulin mimetic; (d) asulfonylurea or other insulin secretagogue; (e) an α-glucosidaseinhibitor; (f) a glucagon receptor antagonist; (g) GLP-1, a GLP-1mimetic, or a GLP-1 receptor agonist; (h) GIP, a GIP mimetic, or a GIPreceptor agonist; (i) PACAP, a PACAP mimetic, or a PACAP receptoragonist; (j) a cholesterol lowering agent selected from the groupconsisting of (i) HMG-CoA reductase inhibitor, (ii) sequestrant, (iii)nicotinyl alcohol, nicotinic acid or a salt thereof, (iv) PPARα agonist,(v) PPARα/γ dual agonist, (vi) inhibitor of cholesterol absorption,(vii) acyl CoA:cholesterol acyltransferase inhibitor, and (viii)anti-oxidant; (k) a PPARδ agonist; (l) an antiobesity compound; (m) anileal bile acid transporter inhibitor; (n) an anti-inflammatory agent;and (o) an antihypertensive agent.